Every couple of childbearing age wants to have a healthy baby, but the total incidence of birth defects in China is about 5.6%. Among the various causes of birth defects, single gene genetic diseases account for about 22.2%. In routine birth examination, children with recessive diseases usually have to show symptoms after birth to find abnormalities. How to check the risk of children suffering from recessive diseases in time?
Without a family genetic history, children will get sick?
According to the data released by the National Health Commission in 2018, it is estimated that the total incidence of birth defects in China is about 5.6%.
Research shows that on average, each normal person carries 2.8 pathogenic mutant genes of recessive diseases. These mutant genes can come from parents or themselves, which may be passed on to the next generation.
Hao Na, a technician in charge of the obstetrics center of Peking Union Medical College Hospital, introduced that single gene genetic diseases refer to genetic diseases controlled by an allele, with more than 9000 kinds, such as progressive pseudohypertrophic muscular dystrophy, spinal muscular dystrophy, thalassemia, phenylketonuria, etc.
The overall incidence rate of single gene disease was 1%, and the genetic pattern of single gene recessive inherited disease was as follows:
Hao Na introduced that when the human body carries the mutant gene of a single gene recessive disease, it is called a carrier. The carrier itself will not get sick, but there is a 50% chance that the mutant gene will be passed on to the child.
When both husband and wife are carriers of the same single gene recessive disease, and the fetus inherits the defective genes of both husband and wife at the same time, it will become a patient in the future. Such couples are 25% more likely to have children with the genetic disease and 50% more likely to have asymptomatic carriers.
In addition, when women are carriers of the pathogenic gene of X-linked recessive diseases, 50% of the boys in each pregnancy and delivery are children and 50% of the girls in delivery are carriers.
Early screening and detection are of great significance
Single gene genetic disease will cause great burden and trauma to patients and their families.
Doctors say that most monogenic genetic diseases will lead to death, serious deformity or disability, and there is a lack of targeted treatment and drugs (only about 5%), so the treatment cost is expensive, and usually only symptomatic treatment or rehabilitation treatment can be taken.
Therefore, it is of great significance for expectant parents to effectively assess, diagnose and identify the risk of common monogenic genetic diseases before or early pregnancy.
Expectant mothers can screen carriers through blood tests during pregnancy or early pregnancy to detect high-risk single gene genetic diseases in order to find out whether there are pathogenic gene mutations.
Jiang Yulin, deputy chief physician of the obstetrics center of Peking Union Medical College Hospital, suggested that patients with highly suspected monogenic diseases, couples with a family history of genetic diseases or having had children with genetic diseases should first carry out genetic diagnosis and investigation on the etiology of their own diseases or family history, and then doctors should suggest whether it is suitable to screen carriers of monogenic diseases.
If it is found that husband and wife are carriers of a single gene genetic disease at the same time, it needs to be combined with genetic counseling, prenatal detection or diagnosis, assisted reproductive technology, etc. It can effectively prevent serious single gene genetic diseases of fetus.
Pregnancy preparation is the best period for screening
Hao Na said that the best time to screen carriers of single gene genetic diseases is pregnancy preparation. During this period, expectant mothers and fathers have enough time, so they are relatively calm when considering and deciding the test results, and there are many alternatives.
Don't worry about missing pregnancy preparation. Early pregnancy screening is also possible. However, this period of time is relatively tight. It is recommended that both husband and wife have a blood test at the same time.
The screening of single gene carriers is simple and rapid. After professional consultation and signing the relevant informed consent in the outpatient department, the husband and wife will take blood test (3 ~ 5 ml of peripheral blood), and the results will usually come out within 3 ~ 4 weeks.
Therefore, couples of childbearing age with fertility intention can screen carriers of single gene recessive inheritance
