congenital defect
any abnormality present at birth, regardless of the cause. It may be caused by faulty fetal development (e.g., spina bifida, cleft palate), hereditary factors (e.g., Huntington’s disease), chromosomal aberration (e.g., Down syndrome), maternal conditions affecting the developing fetus (e.g., fetal alcohol syndrome), metabolic defects (e.g., phenylketonuria), or injury to the brain before or during birth (e.g., some cases of cerebral palsy). A congenital defect may not be apparent until several years after birth (e.g., an allergy or a metabolic disorder) or even until after the individual has reached adulthood (e.g., Huntington’s disease). Also called birth defect; congenital anomaly.