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Hereditary disease

[yí chuán bìng]

Diseases completely or partially determined by genetic factors

synonym Hereditary disease (Hereditary disease) generally refers to hereditary disease

Hereditary disease refers to the disease caused by genetic material Diseases caused by changes or controlled by pathogenic genes. Hereditary disease refers to a disease that is completely or partially determined by genetic factors. It is often congenital or can be acquired. as Congenital stupidity 、 Multifingering (toe) Congenital deafness 、 hemophilia The onset of these genetic diseases is completely determined by genetic factors, and the onset of these genetic diseases occurs after a certain time of birth, sometimes after several years, more than ten years or even decades before obvious symptoms appear.

TCM disease name: Hereditary disease
Foreign name: genetic diseases

Common causes: Diseases caused by changes in genetic material or controlled by pathogenic genes
English name: yichuanbing

catalog

one Basic Introduction
two Main types
three Hereditary disease pathology
four Common genetic diseases and prevention
▪ hypertension
▪ diabetes

▪ surgical treatment
▪ gene therapy
seven Analytical research
eight Clinical characteristics of genetic diseases
nine Appendix: Introduction to Genetics

Basic Introduction

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Disease name

yichuanbing

Hereditary disease

genetic diseases

Disease profile: e.g Duchenne muscular dystrophy To Childhood Just onset; Chronic progressive chorea It is usually in middle age that diseases appear. Some genetic diseases can only be caused by the joint action of genetic factors and environmental factors, such as asthma , genetic factors account for 80%, environmental factors account for 20%; Stomach and duodenal ulcer Genetic factors account for 30%~40%, and environmental factors account for 60%~70%. Genetic diseases often occur in more than one family, which is familial, but it is also possible that there is only one patient in a family, which is sporadic, such as Phenylketonuria , because its pathogenic gene frequency is low Autosomal recessive disease Only when both sides of the couple have a gene that causes the disease, children will become the recessive pathogenic gene Homozygote (Same Gene locus It is not surprising that in families with only one child, sporadic genetic diseases occasionally occur.

Main types

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Type of disease : Diseases caused by changes in genetic material, including chromosome aberration and gene mutation invisible at the chromosome level, are collectively referred to as genetic diseases. According to the change procedure of the genetic material involved, genetic diseases can be divided into three categories:

One is Chromosomal disease Or chromosome syndrome The change of genetic material can be seen at the chromosome level, which is manifested in the change of number or structure. because Chromosomal disease The number of genes involved is large, so the symptoms are usually serious, involving multiple organ and multiple system aberrations and Function change 。

The second is Monogenic disease More than 6500 single gene diseases have been found, mainly a pair Allele The diseases caused by the mutation of Dominant gene and Recessive gene Mutation. so-called Dominant gene It refers to the allele (a pair of Homologous chromosome Control at the same position Relative character A gene that can cause disease as long as one of them is mutated. Recessive gene It refers to the gene that can cause disease only when one allele has mutations at the same time.

The third is Polygenic disease , as the name suggests, this kind of disease involves multiple genes, and Monogenic disease The difference is that these genes don't dominance In relation to recessiveness, each gene only has a slight cumulative effect. Therefore, different people with the same disease may have different disease severity and recurrence risk due to the different number of possible disease genes involved, and show a family aggregation phenomenon. For example, cleft lip may be mild or severe, and some people also have cleft palate 。 It is worth noting that Polygenic disease In addition to being related to heredity, environmental factors also have a considerable impact, so it is also called multifactorial disease. Many common diseases such as asthma 、 cleft lip 、 Schizophrenia 、 Anencephaly 、 hypertension 、 Congenital cardiovascular disease 、 epilepsy Equal Polygenic disease 。

So, can genetic diseases be treated? Previously, people believed that genetic diseases were incurable. In recent years, with the modern medicine In the research of genetic diseases, medical geneticists have made clear the pathogenesis of some genetic diseases, thus providing a certain basis for the treatment and prevention of genetic diseases, and constantly put forward new Treatment measures 。

Hereditary disease pathology

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1. Chromosome abnormality refers to the number or shape of chromosomes Structural anomaly Diseases caused:

A. Structural anomaly Howling cat syndrome (Partial deletion of chromosome 5)

B. Numeric aneuploid chromosomes: Trisomy 21 Syndrome

Sex chromosome: gonadal dysplasia (X0, XXY , XYY )

2. Gene abnormality

A， Monogene

Homologous chromosome Hereditary disease caused by abnormal genes on a pair of chromosomes from the father or mother.

a. Autosomal dominance

（ Achondroplasia ， Polydactyly 、 Polyp of colon ）、

Recessive

（ Albinism ， Phenylketonuria ， Melanuria ， Congenital deafness 、 high myopia ）、

Incomplete dominance （ Thalassemia ）

b. Sex chromosome Ⅰ. The incidence of X-dominant women is higher than that of men

(Xg blood type, also like Vitamin D resistant rickets ）、

The incidence of recessive males is higher than that of females

（ Red green colour blindness 、 hemophilia Etc. are quite common)

II with Y only male onset (hirsutism of external auditory canal)

B. Polygene

Genetic diseases related to more than two pairs of genes. There is no dominant or recessive relationship between each pair of genes, and each disease consists of multiple pairs of genes and environmental factor combined action

essential hypertension , Bronchus asthma , coronary heart disease Adolescent diabetes 、

Rheumatoid arthritis 、 Schizophrenia 、 epilepsy 、 Congenital heart disease 、

Peptic ulcer 、 Varicose veins of lower limbs 、 glaucoma 、 renal calculus 、 Spina bifida 、

Anencephaly 、 cleft lip 、 cleft palate 、 Deformed foot Etc.

Common genetic diseases and prevention

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Hereditary diseases refer to diseases caused by changes in genetic material. It is congenital, lifelong and familial. There are many diseases with high incidence. At present, more than 3000 kinds of genetic diseases have been found, and it is estimated that about 3 to 10 of every 100 newborns suffer from genetic diseases of various degrees.

hypertension

Genetic risk: ★★★★★

Scientists have developed a "genetic spontaneity" hypertension ”Mice. This kind of mice will pass down the gene of hypertension from generation to generation, and 100% of their offspring will have hypertension, which is the most typical example of hypertension closely related to genetics.

At present, most scholars believe that hypertension belongs to Polygene Hereditary diseases. adopt Hypertensive patients The family survey found that if both parents had hypertension, the probability of their children suffering from hypertension in the future was as high as 45%; If one parent suffers from hypertension, the probability of children suffering from hypertension is 28%; The probability of children with normal blood pressure of parents suffering from hypertension is only 3%.

Prevention and control principle

1. Insist on monitoring blood pressure, Normal state At least once a year.

2. Limit salt and supplement potassium. Gradually control the daily intake of salt to 5 grams, and eat more fruits and vegetables rich in potassium (such as Banana 、 Walnut kernel 、 Lotus seed 、 Coriander 、 Amaranth Cuisine Spinach Etc.).

3. Prevent overweight and obesity.

4. Quit smoking and limit alcohol consumption.

diabetes

Genetic risk: ★★★★★

diabetes With obvious Genetic susceptibility (especially the most common Type 2 diabetes ）。 Family study found that there was positive diabetes family history People whose Prevalence of diabetes It is significantly higher than the negative family history group. However, if both parents have diabetes, their children have 15-20 times more chance of suffering from diabetes than ordinary people.

Prevention and control principle

Diabetic“ external cause ”Too many calories, decreased activity, obesity, smoking and Psychological pressure Too large, etc. Conversely, avoiding the above factors can prevent diabetes. In terms of diet, food Meat and egg Reasonably match milk, vegetables and fruits, pay attention to the relationship between intake and Consumption Balance. Always measure your weight. If you gain weight, you must take too many calories. At this time, you should review your Recipes And increase exercise.

Dyslipidemia

Genetic risk: ★★★

There are many reasons for abnormal lipid metabolism, one of which is genetic factors. With the development of medical science, it has been found that there are quite a few Dyslipidemia One or more patients exist genetic genes Defects. from genetic genes The dyslipidemia caused by deficiency mostly has families Aggregation It has obvious genetic tendency and is generally called familial dyslipidemia clinically.

Prevention and control principle

The most important thing is to emphasize "open your legs and control your mouth". On the one hand, diet should be properly restricted, but food types should be as rich as possible, and low-fat food should be selected（ vegetable oil 、 yoghurt ）, increase vitamins and cellulose (fruits, vegetables bread and Cereals ）, control weight. At the same time, strengthen exercise, so that heat consumption will not cause fat accumulation in the body.

mammary cancer

Genetic risk: ★★★

mammary cancer There is obvious familial inheritance tendency. epidemiological investigation It is found that 5%~10% of breast cancer is familial. If a close relative suffers from breast cancer, the risk will increase by 1.5~3 times; If two close relatives have breast cancer Prevalence It will increase sevenfold. The younger the age of onset, the greater the risk of breast cancer in relatives.

Prevention and control principle

Those with family history of breast cancer should pay special attention to self-examination to find breast cancer Early treatment. Breast mass It is the most common sign of breast cancer hyperplasia of mammary glands The masses are different, often single, irregular in shape, hard in texture, poor in mobility, and mostly pain free menstruation The cycle has no obvious relationship. In addition, if any Papillary eczema , spillage and shrinkage should also be paid attention to and further examination should be carried out in the hospital.

gastric cancer

Genetic risk: ★★★

Gastric cancer patients have obvious familial aggregation. The investigation found that First degree relatives (i.e. parents and relatives brothers and sisters ）The risk of gastric cancer is three times higher than that of the general population. The more famous ones are Napoleon The family, his grandfather, father and three younger sisters gastric cancer He died, and seven people in his family, including himself, suffered from gastric cancer.

Prevention and control principle

Suffer from gastric cancer Risk factors Including lack of physical exercise, mental depression, smoking, preference for smoked food, preference for heavy salt diet, excessive intake of meat helicobacter pylori infection 、 gastric ulcer Etc. And happy Fungivore Fresh fruit is a protective factor for gastric cancer. It is worth noting that the phenomenon of family aggregation of gastric cancer may be related to co infection with Helicobacter pylori. People with a family history of gastric cancer should go to the hospital to monitor whether there is such bacterial infection, and if there is, they should be treated in time.

Colorectal cancer

Genetic risk: ★★★

Hereditary Colorectal cancer It accounts for 10%~15% of the total incidence of colorectal cancer. People with colorectal cancer in their relatives are 3 to 4 times more likely to suffer from this disease than ordinary people. If two or more close relatives (parents or siblings) in the family suffer from colorectal cancer, it is colorectal cancer High risk group 。

Prevention and control principle

People with a family history of colorectal cancer should eat more fresh food, less pickled and smoked food, not eat moldy food, drink less alcoholic drinks, and quit smoking. Timely go to the hospital for inspection in case of the following symptoms:

① Change of stool habits , stool frequency increases, or diarrhea It alternates with constipation. ② Stool with pus and blood or Mucinous stool 。③ Stool becomes thin and deformed, and defecation is laborious. ④ Sometimes there is a feeling of defecation, but no stool is released.

lung cancer

Genetic risk: ★★

More than 102000 foreign research institutions Japan The middle-aged and elderly people have carried out Follow up investigation 791 cases occurred among them lung cancer 。 The researcher will Immediate relatives The comparison between the two groups of people with lung cancer and those without lung cancer showed that the former was twice as likely as the latter. The heritability of lung cancer is particularly evident in women.

Prevention and control principle

The occurrence of lung cancer is closely related to smoking, especially those who have a family history of lung cancer must stay away from tobacco and passive smoking. If irritation occurs cough 、 Phlegmatic blood And other symptoms, especially the above high-risk groups Find a doctor Diagnosis and treatment. If early detection and standardized treatment can be carried out cure rate It can reach 70%.

asthma

Genetic risk: ★★★★★

At present, most scholars believe that, asthma The genetic factors of the disease are greater than environmental factor 。 If both parents have asthma The probability of their children suffering from asthma can be as high as 60%; If one of the parents suffers from asthma, the probability of children suffering from asthma is 20%; If neither parent has asthma, the likelihood of children suffering from asthma is only about 6%. In addition, if family members and their relatives have Allergic disease as rhinallergosis 、 skin sensibility Or food Drug allergy And so on, will also increase the risk of future generations asthma Possibility.

Prevention and control principle

adult asthma More in Childhood Incidence, early childhood treatment is reduced Adulthood The key to morbidity. yes asthma Family history person should avoid various environmental factors that cause asthma, such as inhalation of various allergic substances（ Allergen ）, respiratory virus and bacterial infection, smoking, air pollution, etc. These factors play a role in triggering and promoting the onset and exacerbation of asthma. At ordinary times, we should do a good job in cleaning the living, living and working environment, quit smoking, actively prevent and timely treat respiratory tract infection Etc.

depression

Genetic risk: ★★★★★

Many studies have found that depression The occurrence of depression is closely related to genetic factors. The probability of depression among relatives of patients with depression is far higher than that of ordinary people, about 10 to 30 times, and Consanguinity The closer, the higher the probability of illness. According to foreign reports, depression The probability of depression among relatives of patients: 14% of first-degree relatives (parents, siblings, children), Second degree relatives (uncles, aunts, aunts, uncles, grandparents or grandchildren, nephews) 4.8%, Third degree relatives (cousins) 3.6%.

Prevention and control principle

depression The prevention and treatment should focus on early detection, early diagnosis and early treatment. If you often feel depressed, gain or decrease weight significantly, lose sleep or sleep too much, fidget, lose concentration, and have suicidal thoughts, you should go to the hospital in time for examination and treatment.

Alzheimer disease

(commonly known as senile dementia ）

Genetic risk: ★★★

After long-term research, scientists found that, Alzheimer disease Is a kind of Polygenic hereditary disease 。 The study found that people with Alzheimer's disease in their parents or brothers were four times more likely to have Alzheimer's disease than those without a family history.

Prevention and control principle

If you have a family history of Alzheimer's disease, you should check after 50 years old to see if there is any intellectual impairment, so that you can take some measures to treat it in time.

In addition to genetic factors, people with low education level are likely to suffer from Alzheimer's disease and have received regular education Of the people whose illness Age ratio The uneducated were postponed for 7 to 10 years. In addition, long-term depression, living alone, low literacy and language level, widowhood and no remarriage, and no participation social affair And lack of physical and mental activities are also likely to cause Alzheimer's disease.

overweight

The weight genetic factors of obese people account for 25% - 40%. Fat and sweet food Take in and exercise regularly.

osteoporosis

The bone condition of a woman is very similar to that of her mother. Prevention should increase calcium and vitamin D Ingestion of.

erectile dysfunction

Its two major causes are closely related to heredity: first psychological factor Second heart disease 、 Diabetes and hypertension And other factors.

summary

Among them, the incidence of 1~10 types of genetic diseases is about 30%, and there is an increasing trend year by year. Therefore, he can no longer say that genetic disease is only a rare disease. To prevent the birth of children with genetic diseases is to improve China's population quality Important eugenic means. Most genetic diseases cannot be cured. because modern medicine It can't change the genes of people who have already been born, so as long as Pathogenic gene There is no cure. But some diseases can be alleviated by non-stop medication.

Familial hereditary disease

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Hereditary diseases are diseases caused by changes in genetic material.

Hereditary diseases are congenital, familial, lifelong genetic Characteristics of.

The types of genetic diseases can be roughly divided into four categories:

⑴ Monogenic disease

① Autosomal dominant disease : The heredity characteristics are continuous heredity, no sex difference, familial aggregation, etc., such as Achondroplasia 、 Syndactyly 、 Multifingering , Family Polyp of colon Symptoms, etc.

② Autosomal recessive disease : The genetic characteristics are atavism and no sexual difference, such as Albinism 、 Phenylketonuria 、 Congenital deafness 、 Sickle cell anemia , Baby Amaurotic idiocy etc.

③ X chromosome Dominant hereditary disease : Inheritance is characterized by continuous inheritance Cross inheritance . Women are more than men, and the daughters of male patients are all patients, such as Vitamin D resistant rickets 、 Hereditary nephritis Etc.

④ X chromosome Recessive hereditary disease : Hereditary characteristics: Atavism , cross heredity and more males than females, such as hemophilia 、 Progressive muscular dystrophy (pseudohypertrophy) Color blindness Etc.

⑤ Y chromosome hereditary disease: It is characterized by male limited inheritance and continuous inheritance, such as hirsutism of external auditory canal.

⑵ Polygenic disease

It is controlled by multiple pairs of genes and tends to cluster in families. It is difficult to predict and there is no good prevention plan, such as cleft lip 、 Anencephaly 、 essential hypertension 、 Adolescent diabetes Etc.

⑶ Chromosomal disease

Abnormal chromosome number Disease: such as“ Trisomy 21 ”Syndrome, also known as congenital stupidity Down syndrome , due to Chromosome 21 Formed by adding one more line; Gonad dysplasia, also known as Turner's syndrome It is caused by the lack of one female X chromosome. The cause is Meiosis Anomaly formed without Sex chromosome Male and female of gamete With a normal heterotype containing X chromosome Gametogenesis Formed Zygote Developed; Klinefelter syndrome : Male XXY The fertilized egg of such an individual may be formed by a Female gamete With a containing Y chromosome Of Male gamete It may also be formed by combining a normal female gamete with another male gamete containing XY chromosome.

Abnormal chromosome structure Disease: such as Catscream syndrome Because Chromosome 5 Partially missing.

⑷ Cytoplasmic inheritance illness

cytoplasm Genetic material only exists in mitochondrion So cytoplasmic genetic disease is Mitochondrial genetic disease The common case is neuromuscular weakness. Because the cytoplasm in the fertilized egg mainly comes from Egg cell Therefore, cytoplasmic genetic disease depends on female parent , showing the characteristics of "mother's disease and children's total disease".

Basic therapy

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Dietetic treatment

Some genetic diseases can be prevented from happening by controlling diet, thus receiving therapeutic effect. as Phenylketonuria The pathogenesis of Phenylalanine hydroxylase Defect Phenylalanine and Phenylpyruvate It accumulates in the body and causes disease, which may lead to children Mental retardation Or become an idiot. However, if the diagnosis is accurate, it is better to make it in the early stage after birth -10 The prevention and treatment began in the first three days. Within three months after birth, children were given low phenylalanine diet, such as rice Chinese cabbage 、 Spinach , potatoes mutton And so on, can promote the baby to be normal Growth and development 。 When the children grow up and go to school, the restrictions on diet will be appropriately relaxed.

Another example is that 5% of people in provinces south of the Yangtze River in China suffer from heredity glucose 6－ phosphoric acid dehydrogenation Enzyme deficiency Symptoms: Lin Qing's symptoms are Hemolytic anemia In serious cases, it may endanger life. This kind of patient Broad bean Especially sensitive. It can cause acute after eating broad beans Hemolytic anemia , so it is also called“ Broad bean disease ”。 These patients should be strictly forbidden to eat broad beans and their products. At the same time, this disease can also cause drug-induced hemolysis Infectivity Hemolysis and hereditary non Spheroid cell Hemolytic anemia Therefore, you must be careful when using drugs.

medication

Drugs often play an auxiliary role in the treatment of genetic diseases, so as to improve the condition of patients and reduce pain. Mainly Symptomatic treatment , such as taking analgesics to relieve the patient's pain. It can also improve body metabolism, such as Hepatolenticular degeneration , mainly in the body Copper metabolism disorder , which increases the level of copper in the blood, leading to Fetal malformation 。 Drugs to promote copper excretion can be taken, and food containing copper can be restricted to maintain the normal level of copper in the body, so as to achieve good therapeutic effect. Some diseases such as congenital low immunoglobulin Hematemia Immunoglobulin preparations can be injected to achieve the purpose of treatment.

surgical treatment

Surgical correction It refers to the method of surgical resection of certain organs or surgical repair of some organs with morphological defects. Such as sphere Polycythemia , due to Genetic defect Make the patient's red blood cell membrane Osmotic brittleness Significantly increased, red blood cells are spherical, and this kind of red blood cells Splenic sinus It is easily damaged when Hemolytic anemia 。 Can be implemented Splenectomy Although the abnormal morphology of red blood cells cannot be changed after splenectomy, it can prolong the life of red blood cells and obtain therapeutic effect. about Multifingering 、 harelip and External genitalia Deformities, etc., can be corrected by surgery. Another example is:, Body odor It is also a hereditary disease, but as long as the gland with excessive secretion under the armpit is gouged out, the disease can be eliminated.

gene therapy

gene therapy Heredity is a fundamental and promising method. Human genetic material can also be like "shrimp to earthworm The story of borrowing eyes is the same as borrowing from other creatures. That is, normal genes are injected into cells with defective genes to achieve therapeutic purposes. Gene therapy is simple to say, but in fact it is a rather complicated problem. First, we must find out hundreds of thousands of genes Defective gene At the same time, corresponding normal genes must be prepared, and then normal genes can be transferred into cells to replace defective genes, and normal Expression 。 This treatment is still in the stage of research and exploration.

It is worth mentioning that, at the present stage when gene therapy has not been thoroughly studied, only a few genetic diseases can be treated with the above simple methods, and this kind of treatment only serves as a temporary treatment, that is, the so-called "phenotypic treatment" can only eliminate the pain of a generation, while the disease causing gene itself is not touched at all. Those pathogenic genes will, as always, be transmitted to the offspring of patients according to the inherent rules.

Analytical research

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A disease caused by changes in genetic material before or during the formation of a fertilized egg. Some people think that only diseases determined by parents' genetic factors are genetic diseases, which is not comprehensive enough. For example, some chromosome aberrations are not determined by parental genetic factors, but Zygote Produced in the process of formation, habitually chromosome aberration Are included in the category of genetic diseases. Others believe that all diseases affected by genetic factors are genetic diseases, and this concept is not accurate, because in all human diseases, except a few (such as those caused by trauma fracture ）It is completely caused by environmental factors, and is not affected by genetic factors. Almost most diseases are the result of the interaction of environmental and genetic factors, but the degree of their impact on the occurrence of diseases may be different. Even after bacterial infection and trauma epilepsy Diseases with obvious environmental factors, such as susceptibility It is impossible to include these diseases in the category of genetic diseases. Diseases completely determined by genetic factors (Class A, such as trisomy 21 syndrome) and diseases completely determined by environmental factors (Class D, such as Traumatic fracture ）There are only a few, and most human diseases are classified as B and C. Category B refers to that it is basically determined by genetic factors, but it needs certain inducements in the environment to get sick, such as Phenylpyruvuria Children's intake after birth Phenylalanine You will get sick. Class C refers to diseases in which both genetic factors and environmental factors play a role, such as hypertension Disease, infection, etc; But different diseases Heritability Different, that is, the greater the influence of genetic factors, the higher the heritability. So theoretically, A, B and C are all genetic diseases, but C are infectious diseases and post-traumatic diseases epilepsy Etc. is not traditionally included in the category of genetic diseases. Hereditary diseases are different from Congenital disease The latter refers to diseases that have been manifested at birth. Although many genetic diseases have been shown at birth, some genetic diseases are normal at birth, but they begin to show up after several days, months, even years or decades, which is obviously not a congenital disease. On the other hand, congenital diseases are not all caused by genetic factors. For example, pregnant mothers suffer from Radiation Caused by irradiation Congenital malformation Is not a genetic disease. Hereditary diseases are also different from Familial diseases 。 Although some of the same family members have the same genetic basis and can show the family onset of genetic diseases, different genetic diseases Parental generation The transmission laws between offspring are complex and diverse, and some genetic diseases (such as Albinism etc. Recessive hereditary disease ）Maybe not family history On the other hand, familial diseases may also be caused by non genetic factors (such as the same living conditions), such as the lack of vitamin A in the diet, resulting in multiple family members Night blindness 。

In the past, it was thought that genetic disease was a relatively rare disease, but with the development of medicine and people living standard And some infectious diseases that have seriously threatened human health in the past Nutritional disease It can be controlled, and genetic disease has become a prominent problem. For example, a 1914 British survey on the cause of child death showed that non hereditary diseases (such as infection tumour (et al.) accounted for 83.5%, while genetic diseases accounted for only 16.5%, but by the late 1970s, the two types of diseases accounted for 50% respectively. The same is true in China, 1951 Beijing Municipal children's Cause of death Medium, Infectivity Diseases play an important role, but in 1974~1976, children Cause of death analysis Among them, congenital malformations accounted for 23.4% of the total causes of death, ranking first. Among these malformations, 3 to 10 were hereditary diseases. On the other hand, there are many kinds of genetic diseases. With the development of biology and medicine, new genetic diseases have been found one after another in recent years. It shows that the human cognition from 1958 to 1982 Monogenic disease So far, about 4000 genetic diseases have been recognized.

A brief history In the 18th century, the Frenchman Mopperti was the first to make a family survey of genetic diseases, and he analyzed Albinism Of Genetic mode 。 1814 Adams He published a paper on the genetic nature of clinical diseases, which is considered to be the first article in modern times to systematically discuss genetic diseases. 1908 A E. Garrod first put forward the concept of "congenital metabolic abnormality", linking heredity with metabolism, and believed that uric aciduria and other congenital metabolic abnormalities Genetic law Can be used Mendel's law To explain Medical Genetics Has made epoch-making contributions. In 1949, L. Paulin proposed“ Molecular disease ”The concept of. In 1944, Bickel first proposed that controlling neonatal nutrition could effectively prevent the development of phenylpyruvuria, which opened a new chapter for effective treatment of genetic diseases. In 1958, J. Lehrener discovered Congenital stupidity Three for children Chromosome 21 This is the first time to report chromosome abnormalities of genetic diseases. In 1969, Rabbs discovered the fragile part of X chromosome, which opened a new field for the study of chromosome aberration. Since the 1960s prenatal diagnosis Start to apply to clinical. 1978 Kahn For the first time, Heduoqi will DNA recombination technology Applied to the diagnosis of genetic diseases, they diagnosed a case of sickle cell anemia , then this diagnosis technological development Extremely fast.

Classification According to the current level of understanding of genetic material, genetic diseases can be divided into Monogenic disease 、 Polygenic hereditary disease and Chromosomal disease Three categories.

Monogenic disease Homologous chromosome Hereditary disease caused by abnormal genes on a pair of chromosomes from the father or mother. Although there are many kinds of such diseases, more than 3000 (see Table [Number of single gene genetic diseases reported worldwide from 1958 to 1982] Number of single gene genetic diseases reported worldwide from 1958 to 1982) Prevalence Lower, many genera Rare disease 。 Europe and America According to national statistics, about 1% of newborns suffer from severe Genetic disease 。 According to the genetic mode Monogenic disease It can be divided into four categories: ① autosomes Dominant hereditary disease 。 Of the 23 pairs of human chromosomes, one pair is related to sex, called sex chromosome, and the other 22 pairs are called autosomes. A homologous allele on an autosome that is identical to each other is called Homozygote , a pair of genes that are different from each other are called Heterozygote 。 If the abnormal gene can fully show the genetic disease under the heterozygous state, it is called Autosomal dominant disease , such as Syndactyly 、 Congenital myotonia The occurrence of this kind of genetic disease has nothing to do with gender, and the prevalence rate of men and women is the same. If one of the parents suffers from this disease, the child may have the patient. It is estimated that about 7 ‰ of newborns suffer from autosomal dominant genetic diseases. ② Autosomal recessive disease 。 One allele on the autosome must all be abnormal genes Homozygote To show the genetic disease. Most congenital metabolic abnormalities belong to this category. Although the appearance of both parents is normal, if both parents are an autosomal recessive genetic genes Of carrier Their children may still suffer from this genetic disease. Inbreeding It is easy to produce homozygous state, so its children Recessive hereditary disease The incidence rate is also high. ③ Autosomal incompletely dominant disease. This is a genetic disease that can only show symptoms to a certain extent when the abnormal gene is in the heterozygous state. as Thalassemia , the abnormal cause of the disease Homozygote , showing severe anemia, and heterozygotes showing moderate anemia ④ Sex linked hereditary disease 。 It is divided into X-linked genetic diseases and Y interlock There are two genetic diseases. The genes of some hereditary diseases are located on the X chromosome, Y chromosome Too short, no corresponding Allele Therefore, these abnormal genes will be transmitted with the X chromosome, so they are called X-linked genetic diseases. It can also be divided into dominant and recessive. The former refers to a genetic disease that can be manifested by an abnormal gene with one X chromosome. Since women have two X chromosomes and men only have one, women can obtain the Dominant gene There are many opportunities for the disease, and the incidence is higher than that of men. However, there are few genetic diseases of this kind, and only 10 kinds are known so far. Such as Xg blood type, and Vitamin D resistant rickets It is an X-linked incompletely dominant genetic disease. X-linked recessive genetic disease refers to a disease that occurs only when the allele on the X chromosome is homozygous. In women, the disease occurs only when one of the alleles on the two X chromosomes is abnormal. If one of the alleles on the X chromosome is normal, the disease will not occur. But men only have one X chromosome, but as long as the gene on the X chromosome is abnormal, it will show a genetic disease, so the incidence of men is higher than that of women. Such companionship Recessive hereditary disease occupy Sex linked hereditary disease Most of, such as Red green colour blindness , hemophilia, etc. It is estimated that about 1 ‰ of newborns suffer from X-linked genetic diseases. The pathogenic gene of Y-linked genetic disease is located on the Y chromosome, while there is no corresponding allele on the X chromosome. Therefore, these genes are passed from generation to generation along the Y chromosome, also called All male inheritance 。 In humans, Y linked genetic diseases include hirsutism of external auditory canal.

Polygenic genetic diseases are genetic diseases related to more than two pairs of genes. There is no dominant or recessive relationship between each pair of genes, and each pair of genes has little effect alone, but each pair of genes has Cumulative effect 。 Generally speaking, polygenic diseases are far more common than monogenic diseases. Influenced by environmental factors, different polygenic genetic diseases are affected to different degrees by genetic factors and environmental factors. The degree of influence of genetic factors on disease occurrence can be explained by heritability, which is generally used percentage The higher the heritability, the greater the influence of genetic factors on this polygenic genetic disease. For example, cleft lip and cleft palate are polygenetic diseases, with heritability of 76%, while ulcer Only 37%. Polygenic genetic diseases also include some diabetes , hypertension Hyperlipidemia 、 Neural tube defect 、 Congenital heart disease , schizophrenia, etc. In the population, the prevalence of polygenic genetic diseases is more than 2-3%.

Chromosome disease refers to the disease caused by abnormal number, shape and structure of chromosomes. The incidence of chromosomal abnormalities in neonates is 0.5%. Chromosome abnormality is called chromosome aberration, including autosomal abnormality and sex chromosome abnormality. however Chromosomal disease It accounts for a small proportion of all genetic diseases, only about 1/10.

Research and diagnosis of genetic diseases: to study and judge whether a disease is a genetic disease, the following ways can be used: family investigation and analysis, analysis of twins, ethnic comparison, research on accompanying traits animal model and DNA analysis. Through pedigree investigation, analysis and comparison with the incidence of the population, we can not only judge whether a disease is a genetic disease, but also further determine its genetic mode if it is a genetic disease. adopt Monozygote The analysis of the concordance rate of twin and twin twins may determine the extent to which a disease is affected by genetic and environmental factors. Comparison of morbidity among different races and nationalities, especially for the same environment The study on the incidence of different races may provide important clues for the judgment of genetic diseases. In the analysis of concomitant symptoms, allogeneic leukocyte antigens are most commonly used at present（ HLA ）The system is used as a marker of genetic diseases. The research is carried out as an accompanying trait of a certain heredity linkage analysis , it can also provide a basis for the judgment of genetic diseases. At present, dozens of animal models of chromosome aberration and single gene genetic diseases have been established, which provides a powerful means for the research of genetic diseases. DNA analysis is an important means developed in recent years, in which the fragment length is limited Polymorphism （ RFLP ）Analysis is most widely used in genetic disease judgment.

Hereditary clinical diagnosis More difficult than other diseases. On the one hand, there are many kinds of genetic diseases, on the other hand, the individual incidence of each genetic disease is very low, so Clinician It is not easy to gain experience in the diagnosis of genetic diseases. Except for common diseases diagnostic method (e.g. medical history, physical examination, laboratory and Instrument inspection ）In addition, the diagnosis of genetic diseases may also rely on some special diagnostic methods, such as chromosome examination, special biochemical determination and Genealogical analysis 。 Hereditary clinical manifestation It is the most important diagnostic clue. Every genetic disease has some symptoms and signs at the same time, which is called "syndrome". This is the initial clue to prompt diagnosis and also a choice laboratory examination And others genetics Basis of inspection. For patients with genetic diseases, it is necessary to inquire about the family history in detail and draw an accurate and reliable pedigree. The analysis of pedigree is not only Genetic disease diagnosis And the identification and implementation of genetic mode Genetic counseling It is also extremely important. Dermatoglyph Analysis is another special means of genetic disease diagnosis, mainly for Chromosomal disease It is the most valuable, and may also have some significance for other individual single gene genetic diseases. Fingerprints palm prints 、 Palmar pleat , finger wrinkles and foot palms. Many hereditary diseases Final diagnosis It also depends on chromosome examination and special biochemical determination or DNA analysis.

Prenatal diagnosis is an important aspect of genetic disease diagnosis, which is obtained by puncture before the birth of a baby amniotic fluid or Villous tissue 。 Chromosome examination, specific enzymatic activity or Metabolites Determine, or conduct DNA analysis to judge the fetal morbidity, and decide whether to conduct artificial abortion with terminal pregnancy , which is reducing the birth of children with genetic diseases and improving the population quality It is of great significance to prevent the birth of children with genetic diseases by terminating pregnancy, especially under the condition that most genetic diseases cannot be effectively treated by humans at present. In recent years, due to B-mode ultrasound Scanner With the wide application and improvement of technology, it has great value in prenatal diagnosis, especially in the diagnosis of developmental malformations. Fetoscope It has also been applied to prenatal diagnosis.

gene diagnosis It is a newly developed important technology, and can also make accurate diagnosis of nearly 100 kinds of genetic diseases. However, most of these genetic diseases cannot be effectively treated medical ethics In addition to prenatal diagnosis, there are still big problems in the promotion of genetic diagnosis.

To cure and prevent genetic diseases, we should correct the existing defects at the gene level or chromosome level. This method is called gene therapy , of genetic engineering Category of. However, there are still great difficulties in the theory and technology of gene therapy, which can not be used clinically at present. At present, the treatment of genetic diseases can only be carried out in early diagnosis By controlling environment condition (such as dietary ingredients), regulate the metabolic process and prevent symptoms, which is called "environmental engineering". Current treatments that can be applied to environmental engineering include diet control therapy (such as Phenylketonuria Use low or none Phenylpyruvate Milk powder feeding) Pharmacotherapy (If vitamin B6 is used to treat B6 dependence, allopurinol is used to treat it gout Etc.) surgical treatment (e.g splenectomy treatment Hereditary spherocytosis ）Supplement of enzymes (such as Allogeneic bone marrow transplantation treatment Gaucher's disease ）And Symptomatic therapy (If anti epilepsy Drug control of phenylpyruvuria convulsions ）Etc. Although environmental engineering can alleviate or eliminate the symptoms of some genetic diseases and is beneficial to individuals Treatment results However, patients with disease causing genes can not only survive, but also continue to reproduce. These patients can be eliminated naturally without treatment, at least they will not reproduce. Therefore, the impact of environmental engineering on the whole mankind may be harmful, which will increase the frequency of pathogenic genes in the population generation by generation, thus leading to an increase in the incidence of genetic diseases.

Because there is no effective treatment for most genetic diseases at present, the prevention of genetic diseases is of special significance. preventive measure include Newborn screening , environmental protection carrier And genetic counseling. Neonatal screening refers to the simple examination of a certain genetic disease for all babies born, so as to start treatment before symptoms appear and prevent symptoms from occurring. Only those who can find biochemical abnormalities through inspection before symptoms appear, and have Treatment measures , and failure to give treatment will cause Severe disability Neonatal screening was carried out only for genetic diseases. Phenylpyruvuria and congenital hypothyroidism have been listed as legal newborn screening items in many countries. In Beijing, Shanghai, Tianjin Wuhan Some screening has also been carried out in other places. Among them, the phenylpyruvuria screening published in 1985 in 12 provinces and cities across the country is the first large-scale neonatal screening reported in China. Biotin The neonatal screening for enzyme deficiency is also a new topic in the world. China has started this screening work in Beijing since 1987. Environmental protection refers to the reduction or elimination of Teratogens 、 Carcinogen Chromosome aberration agents and gene mutagens are mainly pollution produced in industrial and agricultural production. carrier Detection refers to the detection of individuals with normal appearance but with pathogenic genes or abnormal chromosomes from the population to guide their marriage and fertility and prevent their offspring from suffering from this genetic disease. The detection method is mainly chromosomal examination and specific Enzyme activity measurement Or metabolite determination and DNA analysis balanced translocation And more than 100 species Monogenic disease The detection of carriers is of great significance for the prevention of these genetic diseases. Genetic counseling, which first appeared in the United States in 1952 and was launched in China after the 1970s, is a way for medical personnel to understand the etiology, genetic mode, prevention, treatment prognosis , as well as the answers to the questions raised, and to the patients' siblings who suffer from this disease again Risk rate Make estimates, give advice and guidance. It can be considered that genetic counseling, prenatal diagnosis and termination of pregnancy are the "trilogy" to prevent the birth of patients with genetic diseases. Someone took Marriage Counseling And fertility counseling are also included in the scope of genetic counseling Eugenics It is of great significance.

Clinical characteristics of genetic diseases

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1. Patients have special phenotype (usually accompanied by Mental retardation ）And chromosomal abnormalities

2. On the premise of removing the influence of environmental factors, there are patients in relatives and they are ill in a certain proportion

3. In the absence of Consanguinity The patient does not appear in the members of (such as husband and wife)

4. The patient has specific onset age, course characteristics and clinical manifestations

5, at twins Medium, Monozygotic twins Is higher than Dizygotic twins .

Appendix: Introduction to Genetics

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The research scope of genetics includes genetic material The essence of genetic material, transmission and genetic information Three aspects of realization. The essence of genetic material includes its Chemical essence The genetic information it contains, its structure, organization and changes; The transmission of genetic material includes the replication of genetic material, the behavior of chromosomes Genetic law And the quantitative changes of genes in the population; The realization of genetic information includes the original function of genes, gene interaction, Gene action Regulation and Ontogeny The mechanism of action of genes in.

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