What Are Genetic Birth Defects?

"Birth defect", which is commonly referred to as "congenital malformation", refers to the abnormal structure, function, or metabolism of a baby that occurs before birth. Birth defects can be caused by genetic or environmental factors such as chromosomal aberrations, gene mutations, or the interaction of these two factors or other unknown causes. They usually include congenital malformations, chromosomal abnormalities, genetic metabolic diseases, and functional abnormalities (such as blindness, Deaf and mentally retarded, etc.).

Basic Information

TCM disease name

Congenital malformation

Multiple groups

obstetrics

Contagious

Anencephaly, hydrocephalus, open spina bifida, meningocele, cleft lip, cleft palate, congenital heart disease, trisomy 21

Causes of birth defects

At present, the specific cause of most birth defects is still unknown, but many factors are known to cause birth defects, of which environmental factors account for about 10%, genetic factors account for about 25%, and the interaction between environmental factors and genetic factors and Unexplained people account for about 65%.

Common causes of birth defects are:

Own factor

(1) Self-genetic factors Any one of the parents has genetic factors that may affect the fetus. For example, parents who have had birth defects of neural tube defects are pregnant again, and the rate of congenital neural tube defects is 3 times higher than that of normal people.

(2) The most common maternal factors are viral infections such as rubella, influenza, and toxoplasma infection during pregnancy, or diseases associated with pregnancy, such as syphilis, AIDS, and cytomegalovirus. The mother suffers from an infectious disease during pregnancy. The pathogen can infect the fetus through the placenta, causing fetal dysplasia and deformity, or causing miscarriage and stillbirth. In addition, due to infection, maternal fever, shock, hypoxia, etc. can also cause fetal malformations. Mothers with diabetes may cause stillbirths and high stillbirths; high rates of malformations include heart, neural tube defects, gastrointestinal, and skeletal deformities; giant children; hypoglycemia in newborns. A mother with hyperthyroidism may have transient or persistent hyperthyroidism in the newborn. The former has a good prognosis, while the latter has premature bone age, small head, low intelligence, short body, etc. The prognosis is poor. In addition, the early fetus is most susceptible to teratogenic effects, especially the period affected by drugs. It is most sensitive in the early development stage (3 to 4 days after fertilization to 9th week of pregnancy), especially 6 to 9 weeks. The formation of fetal organs. A mother's infection or improper use of medication can cause birth defects.

(3) Nutritional deficiency of trace elements during pregnancy, such as folic acid, vitamin B family, and excess or lack of nutrition.

2. Environmental factors

(1) Ray, noise, high temperature and low temperature.

(2) Chemical pollution and food pollution are teratogenic. Mainly from various chemical pollution of the atmosphere, soil, water, medicines, food additives, condiments, cosmetics, including mercury, lead, mercury chloride, polychlorinated biphenyls, pesticides and floating dust containing harmful substances such as carbon monoxide and nitrogen oxides Such as direct contact and indirect environmental pollution, but also the lack of certain trace elements of the human body, such as zinc, selenium, copper, manganese, iodine and so on. For modern women, the harmful effects on fetal malformation may be arsenic, lead, mercury and other toxic substances contained in cosmetics. After being absorbed by the skin and mucous membranes of pregnant women, they can pass through the blood-fetal barrier and enter the fetal blood circulation. Affects the normal development of the fetus.

(3) Poor habits such as smoking and drinking, including the pollution of second-hand smoke, and drug and soft drugs have a direct impact.

Clinical manifestations of birth defects

Common birth defects:

1. Central nervous system: hydrocephalus, meningocele, spina bifida, etc.

2. Head, face and neck: cleft lip, palate, lymphangioma, etc.

3. Chest: Congenital diaphragmatic hernia, congenital pulmonary cystic adenomatous deformity, lung isolation, fetal pleural fluid, congenital larynx, tracheal atresia / stenosis and congenital esophageal atresia

4. Gastrointestinal malformations: abdominal wall defects, congenital diaphragmatic hernia, intestinal atresia, umbilical bulge.

5. Urinary system: hydronephrosis, bladder ureteral reflux, giant ureter, renal cystic change.

6. Limbs: Multi-finger and fingers deformity, lack of limbs or compression of ring cord.

7. Tumors: Except for giant lymphangiomas of the neck, the most common are zygomatic tail teratoma, followed by ovarian tumors and abdominal and chest tumors.

Diagnosis of birth defects

Common diagnostic techniques are:

1.B-ultrasound

It can not only detect malformations in the fetal body structure, but also detect visceral developmental malformations. It is the most widely used method at present, and the examination time is generally 18 to 22 weeks of pregnancy.

Ultrasound imaging during the second trimester can be more and more accurate for detecting abnormalities in the structure of the fetus. Prenatal ultrasound examination can find the following abnormalities: such as abnormal amniotic fluid volume (too much, too little); intrauterine growth retardation of the fetus; fetal edema; head and facial deformities; neural tube malformations; gastrointestinal malformations; urinary malformations are all fetuses The content of the assessment and its results have important guiding significance for the management of pregnancy.

2. Amniotic fluid inspection

It is advisable to take samples at 16 weeks of gestation, and to diagnose genetic diseases and some abnormalities through cell culture, alpha-fetoprotein (AFP) measurement, and enzymatic examination; it is mainly for the detection of major genetic abnormalities.

3.MRI examination

With the development of MRI technology, and its advantages such as no radiation damage, multi-section imaging, wide field of view, and good soft tissue contrast resolution, it has become an important supplement for ultrasound diagnosis. The radio frequency of MRI is several meters, and the energy is only 10-7ev, which is safer for the fetus. MRI can prompt more details of fetal congenital structural malformations. MRI is used to diagnose fetal chest malformations, especially for atypical lesions, or combined with a variety of complex malformations can make up for the lack of ultrasound diagnosis. Prenatal MRI can provide stereoscopic, homogeneous images, and clearly show blood supply. Better prediction of fetal outcomes after birth. It is helpful for comprehensive prenatal assessment of the fetus and the development of a post-natal treatment plan. Therefore, prenatal MRI is more effective than B-ultrasound.

Birth defect assessment treatment

The advantages of prenatal fetal surgery evaluation: With the prenatal diagnosis, the diagnosis and treatment of neonatal surgical diseases have a good premise and treatment basis. Before the fetus is born, the pediatric surgeon will analyze the possible complications after birth, Make a detailed explanation with the parents of the fetus about the upcoming surgical treatment and the cost of the family's investment. When the fetus is born and after birth, there will be targeted prevention of complications. Postnatal diagnosis and treatment will be According to the plan, the diagnosis and treatment of neonatal surgical diseases are no longer a passive situation in the past, and the diagnosis and cure rate of neonatal surgical diseases have also increased.

Birth defect prevention

Prenatal diagnosis should be performed in any of the following cases: pregnant women over 35 years of age; those who have had congenital diseases such as malformed children or congenital babies, and the spouse has a genetic or chromosomal disease, and has a habitual abortion, premature birth , Stillbirths, neonatal deaths, and other history of adverse pregnancy, those who have been exposed to large doses of radiation in early pregnancy, or who have been infected by a virus or who have taken teratogenic side effects for longer periods of time.