Sunday, April 20, 2014

Eugenics intervention for genetic disease away from the baby

Recently, the news aroused people focus on genetic disorders: one of the cartilage disease pregnant woman got married, had been termination of gestation, the doctor suggested that genetic risk for 50% of the disease.



The hereditary disease is what disease? How do they happen? Is there any way to treat now? This is the common concern of the people.



Genetic epidemiologist recently, the reporter interviewed on these problems, for genetic disorders, people always thought that is "doomed" "incurable disease", in fact, as for human genetic disorders research gradually thorough, for some genetic diseases, people have to decipher the "genetic code", adopt scientific method to intervene, can help reproductive health smart baby.



Genetic disease is what disease?



Hubei maternal and child health care center of genetic Song Jieping director introduces, hereditary disease, is refers to the genetic material of germ cells or fertilized eggs (chromosome and gene mutation or distortion caused by the disease. About four thousand kinds of known genetic disorders. Including chromosome disease, but gene disease and three types of polygenic disease.



Director of the song dynasty said it was easy for people to confuse genetic diseases and congenital diseases. Actually, congenital diseases generally refers to the baby born showed symptoms of the disease. Some of congenital diseases are caused by genetic factors, is a genetic disease, such as congenital down (down syndrome); But some is affected by the external adverse factors during pregnancy and cause abnormal fetal development, are not of the hereditary disease categories, such as congenital heart disease. "Accordingly, congenital disease Disease are not hereditary disease.



Hereditary disease, on the other hand, may not have symptoms at birth, that is to say, the emergence of some acquired diseases may also be a genetic disease. Some genetic disorders, table now until a certain age in individual development. For example, progressive muscular dystrophy, usually the disease at the age of 4 ~ 6. Many patients with hereditary mental retardation in babies also not easy to find. In a disease, therefore, the day after tomorrow, also have a genetic disease.



Hereditary disease, experts point out that, in fact, is not terrible and complicated diseases, as long as we understand it, is there a way to control it.



Prevention of genetic diseases to good "three pass"



The first level: the premarital health examination



Has identified a relationship of men and women, before the marriage registration formalities should make a comprehensive system of health check. Especially note that avoid inbreeding.



Relatives refers to the three or four generations have a common ancestor. Our country marriage law regulation blood relatives within three generations of marriage is prohibited. According to the world health organization estimates that each person in the crowd carry about 5 ~ 6 kinds of recessive genetic disease cause of disease genes. In random mating (not relatives mating), as there is no blood relationship, the couple rarely the same genes, they carry the recessive gene, and therefore is not easy to form a recessive gene of pure fit (patients). In inbreeding, couple with the same possibility of recessive gene is very big, easy to meet in the offspring, and make the higher incidence of genetic disorders of offspring. The incidence of common cleft lip, for example, the average person is only 0.17%, and cause the incidence of inbreeding was as high as 4%. Inbreeding descendants suffer from mental retardation, congenital abnormalities and various geometric non more several times as marriage between first Cousins.



Pregnancy: second, genetic counseling



Once birth to children with congenital down couple often wonder, they are very normal, in the family never had a similar disease, why gave birth to this kind of congenital mental retardation case? The expert points out, if until the next pregnancy to prevent genetic disease awareness, do a genetic counseling, should be able to avoid the tragedy again.



Director of the song dynasty, said can marry but not birth in the following circumstances:



Either (1) men and women suffering from a serious autosomal dominant genetic disease, such as ankylosing muscular dystrophy, achondroplasia, osteogenesis hypoplasia, spinal cord cerebellar ataxia, marfan's comprehensive character, as well as the genetic blinding eye diseases such as retinoblastoma, dominant inheritance bilateral congenital microphthalmia etc. Because the genetic disease risk is higher, and there is no effective method for treatment and prevention. Osteogenesis hypoplasia, for example, commonly known as "glass", this is a major involvement bones, tendons, fascia, ligaments, dentin and sclera of the disease. Its typical characteristics of bone brittleness increases, easy to fracture, therefore is also called "cartilage disease". It belongs to autosomal dominant genetic disease, husband and wife any one party sicken, children have a 50% risk. And for patients with women, itself is a high-risk pregnancy, abortion, stillbirth, defects may occur, and even endanger pregnant woman's life, so it is unfavorable.



(2) both sides of husband and wife have the same serious recessive genetic disease such as pituitary dwarfism, microcephaly, benzene acetone urine, liver degeneration and so on.



(3) male and female, one party suffers from severe polygene genetic disorders such as schizophrenia and manic depressive psychosis, more fortune for high. High fortune is refers to in addition to the patients themselves, their parents or brothers and sisters in one or more people suffering from the same genetic disease.



The third clearance: prenatal screening to avoid children born



Prenatal screening some no good mainly for the treatment of diseases, the purpose is to prevent defective child was born. Generally at 16 to 20 weeks pregnant, peripheral blood in pregnant women who smoke 2-3 ml to check, if it is found that high risk probability (risk factors more than 1/270), will be expected to further smoke amniotic fluid, confirmed. Such as down's syndrome can be through the sieve out down syndrome screening high-risk pregnant women, prenatal diagnosis for the smoke through the amniotic fluid to confirmed. If osteogenesis hypoplasia, again by prenatal ultrasound fetal system at present, which can effectively prevent patients was born, is also the main measures of prevention and cure of the disease. On some single gene genetic disorders, such as progressive muscular dystrophy, now can make prenatal gene diagnosis, if both sides of husband and wife as the carrier, has a births, children can be carried out on the next child gene check, check if the fetus with disease-causing genes, can be induced labor avoid the children born.



Genetic disease is not an incurable disease



Ago, people think that genetic disease is an incurable disease. Now, medical genetics, workers in the study of genetic disorders, and find out the process of some genetic disorders, thus provides the genetic disease treatment and prevention of the basis of a set, and constantly new treatment measures are put forward. As for patients with symptoms of genetic disorders, can through diet, medication, surgery, and gene therapy to achieve the goal of improved or cured.



Dietary treatment of certain genetic disorders can achieve the purpose of preventing disease through diet, to receive the treatment effect. Such as benzene acetone urine disease pathogenesis is phenylalanine hydroxylase defects, phenylalanine and styrene acrylic ketone accumulation of acid in the body disease, can appear in children with mental retardation or become an idiot. Best but if correctly diagnosed, early prevention and control of 7 to 10 days after birth start, within 3 months after birth, giving children a low phenylalanine diet, such as rice, cabbage, spinach, potato, mutton, etc., can make baby normal growth and development. By the time the children go to school, then appropriate to relax the limitation on the diet.



Drug therapy in the treatment of genetic disorders often play a supporting role, can improve the patient's condition, reduce the pain. Such as liver degeneration, mainly copper in the body metabolic disorders, make the blood levels of copper in liters High, lead to fetal abnormalities. Can promote copper excretion of drugs, at the same time limit consumption of food containing copper, to maintain the normal level of copper in the body, and good treatment effect. Also some diseases such as congenital low immune globulin blood disease, can inject immunoglobulin preparations, in order to achieve the purpose of the treatment. Congenital low thyroid function will be given to the right amount of thyroid hormone and regular monitoring, to ensure the normal growth and development of children.



Surgical excision surgery fixed surgically refers to using some organs or surgery for some defects with configuration organ repair methods. Such as spherical disease of grow in quantity of red blood cells, as a result of genetic defects of red cell membrane permeability and brittleness of patients significantly increased, erythrocyte spherical, the red blood cells in the spleen of splenic sinus vulnerable to damage and cause hemolytic anemia. Can implement splenectomy, after splenectomy, although can't change the abnormal form red blood cells, but it can prolong the life of red blood cells, access to treatment effect. For multiple means, cleft lip and genital malformation, but by surgical correction. Another example, body odor is also a kind of hereditary disease, but as long as the patient armpits excessive secretion of gland tear drop, can eliminate patients.



Gene therapy to treat hereditary disease is a fundamental and promising method. Cells with normal gene to gene defects, to achieve therapeutic purposes. Is simple, but in fact is a quite complex problem. Must first find out the faulty gene from hundreds of thousands of genes, must be produced at the same time the corresponding normal gene, and then replace faulty gene in normal genes into the cells, and can be normal expression. This kind of treatment method, it is in the phase of research and exploration.



Deserve special is put forward, in gene therapy has not been completely developed at present, genetic disorders can be used the above several simple methods for treatment, after all is a minority, and only treats the symptoms of this kind of treatment effect, the so-called "phenotype" treatment, can eliminate the generation of sickness, and pathogenic gene itself is not touched. The pathogenic genes will, as always, according to the inherent law is passed to the patient's descendants.