Congenital malformations, or congenital malformations, are the defective formation of structures or parts of the body present at birth. Sporadic, hereditary or acquired malformations may be immediately observed or manifest later in life; they may be visible on the surface of the body or present internally. Birth defects can be life-threatening and require surgical correction, or they can interfere with function or appearance. It is estimated that approximately 3% of all children are born with major malformations; It is estimated that minor anomalies or variations occur in 10 to 15% of births. Malformations can be single or multiple. Multiple malformations that occur in a recognizable, regular pattern are called syndromes - for example, FETAL ALCOHOL SYNDROME sometimes seen in infants of mothers who drank heavily during pregnancy. Birth defects can result from the action of genes, chromosomes, or the environment on the developing fetus, but the cause often cannot be determined. Hereditary defectsAbnormal genes cause a significant number of different birth defects. Some can be identified as a monogenic disorder inherited in a simple Mendelian fashion, that is, a dominant or recessive pattern. For example, lobster claw deformity of the hands and feet (cleft hands or feet) is hereditary and results from the effect of a single dominant gene. A person affected by this malformation runs a 50% (1 in 2) risk of having offspring who will inherit the gene and therefore also be affected. Autosomal reception...