ABSTRACT
Dysmorphology is the study of malformations and birth defects. Abnormal development may be due to a chromosomal abnormality, a single gene defect or a teratogen, or may be multifactorial. Recognition of patterns of multiple congenital abnormalities may help in identifying the aetiology and is important in counselling parents about prognosis, management and risk of recurrence. The majority of single malformations have a multifactorial inheritance and a low recurrence risk. Multiple malformations, particularly when associated with learning difficulties, are more frequently due to a single gene defect or a chromosomal abnormality and the recurrence risk is higher.
