Classification of birth defects

Single system defects
Single system defects constitute the largest group of birth
defects, affecting a single organ system or local region of the
body. The commonest of these include cleft lip and palate, club
foot, pyloric stenosis, congenital dislocation of the hip and
congenital heart defects. Each of these defects can also occur
frequently as a component of a more generalised multiple
abnormality disorder. Congenital heart defects, for example,
are associated with many chromosomal disorders and
malformation syndromes. When these defects occur as isolated
abnormalities, the recurrence risk is usually low.