Congenital anomaly is a mental or physical abnormality that is present at, and usually before, birth. Some anomalies may be medically insignificant and may not appear for some time. In other cases, the anomaly may pose a direct threat to life and requires immediate attention. There are, however, some anomalies that cannot be treated.
Question: What are examples of congenital anomalies?
Congenital anomalies include bone disorders, cataract, cleft palate, cretinism, Down’s syndrome, congenital heart disease, hemophilia, joint disorders, pyloric stenosis, and spina bifida. Blindness, deafness, hydrocephalus, and jaundice are also often due to congenital anomalies, although in other cases they are the result of event that occurred after birth.
Limbs or organs may be malformed, duplicated, or entirely absent. Organs may fail to move to the correct place, as in cryptorchidism; fail to open correctly as in imperforate anus; or fail to close at the correct time, as in patent ductus arteriosus. Congenital anomalies often occur together. For example, 33 percent of babies born with Down’s syndrome also have heart disease.
Question: What may cause the development of congenital anomalies?
Congenital anomalies arise from the faulty development of a fetus, caused either by genetic disorders or other factors. Some anomalies arise from a combination of factors, and the underlying cause is far from clear in all cases.
Question: How are genetic disorders responsible for congenital anomalies?
Inherited congenital anomalies generally result from the presence of abnormal genes or chromosomes. Heredity is determined by corresponding pairs of genes, called alleles. One of these paired genes is dominant and the other recessive, and it is the dominant gene that governs the transmitted trait or characteristic. Thus, if the abnormal gene of a pair is dominant, the abnormal or anomalous trait will be conveyed to the embryo. If the abnormal gene is recessive, then both genes in the pair have to be abnormal for a congenital anomaly to occur.
