Congenital Anomalies: Causes, Symptoms, Treatment
Overview
Congenital anomalies are defined as structural or functional anomalies that occur in utero or at birth, sometimes can only be detected later in infancy. They are also known as birth defects, congenital disorders or congenital malformations. Congenital anomalies are caused by a hereditary or developmental disability or disease.
The most common and severe congenital anomalies are heart defects, neural tube defects and down syndrome. Congenital anomalies can lead to infant and childhood deaths, chronic illness and disability. About 3% to 4% of babies born in the United States have congenital abnormalities.
Causes
It is difficult to identify the exact causes of congenital anomalies. However, there are many risk factors which may be associated with congenital anomalies, including genetic, infectious, nutritional or environmental factors.
- Genetic factors
Genes play an important role in congenital anomalies. Congenital anomalies might result from inherited genes or sudden changes in genes known as mutations. Genetic causes include chromosomal defects, single gene defects, recessive inheritance and dominant inheritance.
- Infectious factors
Maternal infections such as syphilis and rubella are a significant cause of congenital anomalies, especially in some low- and-middle income countries.
- Nutritional factors
Maternal folate insufficiency and malnutrition also increase the risk of having a baby with a birth defect, and excessive vitamin A intake may affect the normal development of a fetus.
- Environmental factors
Maternal exposure to certain chemicals, as well as certain medications, alcohol, tobacco and radiation during pregnancy, may increase the risk of having a fetus or baby with congenital anomalies. Besides, working or living near waste sites, smelters or mines can also be a risk factor.
Symptoms
There are different types of congenital anomalies, which have different symptoms. Many congenital anomalies are related to bone or skeletal system growth, such as clubfoot, fused fingers or hands, unusual growth or lack of growth of skeletal structure, and congenitally shorter limbs, as is the case in children with Down syndrome. Cleft palate may also be in this grouping, and severe clefts can affect the sinuses and breathing. There are also congenital anomalies of the reproductive system and the urinary tract.
Diagnosis
Diagnosis of congenital anomalies can help parents emotionally prepare for a child with a birth defect. Some birth defects can be diagnosed before birth through amniocentesis or chorionic villus sampling (CVS) and other tests.
- Amniocentesis
During pregnancy, foetus is surrounded by amniotic fluid that can be used to detect genetic disorders in the foetus.
- Chorionic villus sampling (CVS)
In this test, cells from the chorionic villi will be examined for chromosomal disorders such as Down syndromes.
- Blood tests
Most women have blood tests to screen for their risk of having a baby with a specific birth defect, such as Down syndrome and spina bifida.
- Cell-free fetal DNA testing
It is a noninvasive prenatal screening that uses cell-free DNA from the plasma of pregnant women as a screening method for fetal aneuploidy.
- Infection screening
Infection screening can determine if a woman has a urinary tract infection or other types of infection that can be harmful to her or the fetus.
- Cordocentesis
It is an invasive diagnostic test. In this test, a small sample of the foetal blood is withdrawn from the umbilical cord for detection of foetal abnormalities after 17 weeks of pregnancy. This test can detect chromosome abnormalities and certain blood disorders.
In other cases, a birth defect is diagnosed after birth through physical examination or a blood test that screens for several disorders in newborns.
Treatment
Most birth defects cannot be cured. However, about 50% of structural congenital anomalies can be corrected with paediatric surgery in early life, such as simple congenital heart defects, cleft lip and palate, club foot, congenital cataracts, and gastrointestinal and urogenital abnormalities.
There are also some treatments which can help manage the symptoms, including:
- Gene therapy
Gene therapy replaces a gene that is missing or defective. So far, gene therapy has been used to treat some severe combined immunodeficiency diseases (SCID), which are a group of rare diseases.
- Enzyme replacement therapy
Enzymes are proteins for which genes code. When a gene is mutated and does not produce the gene product, an enzyme is missing or defective. To treat this type of genetic defect needs replacing the enzyme that the gene cannot produce.
Gaucher disease is an example of the condition which can be managed by enzyme replacement therapy.
- Prenatal treatment
Some birth defects can be diagnosed and treated before birth. For example, prenatal surgery can treat babies with urinary tract blockages and rare lung tumors.
Keywords: congenital anomalies.
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