Craniofacial and musculoskeletal abnormalities are common among children. They may involve only a single, specific site (eg, cleft lip, cleft palate, clubfoot) or be part of a syndrome of multiple congenital anomalies (eg, velocardiofacial syndrome, Treacher Collins syndrome). Careful clinical assessment may be necessary to distinguish an isolated abnormality from an atypical or mildly manifested syndrome.

Congenital abnormalities may be classified as deformities or malformations.

A deformity is an alteration in shape due to unusual pressure and/or positioning in utero during late pregnancy. Deformities are present in about 2% of births; some resolve spontaneously within a few days, but others persist and require treatment.

A malformation is an error in normal organ or tissue development. Causes include chromosomal abnormalities, single-gene defects, teratogenic agents, or a combination of genetic and environmental factors; a decreasing number of cases are idiopathic. Congenital malformations are present in about 3 to 5% of births. A clinical geneticist should assess affected patients to establish a definitive diagnosis, which is essential for formulating an optimal treatment plan, providing anticipatory guidance and genetic counseling, and identifying relatives at risk of similar abnormalities.