Malformations

Malformations are congenital structural defects that arise from abnormal development in the embryo and are present at birth. They can affect any organ system and range from minor anomalies to major defects that require urgent intervention. Malformations are distinguished from deformities, which result from external forces altering a normal structure later in gestation, and from disruptions, where tissue is destroyed after initially forming.

Causes and classification: Malformations most often reflect a complex mix of genetic and environmental factors, including single-gene mutations, chromosomal abnormalities, or multifactorial influences. Environmental teratogens (such as certain medications, alcohol, or maternal infections) and maternal conditions (for example, diabetes) can increase risk. Malformations are commonly categorized by mechanism (formation, differentiation, or growth disturbances) or by affected organ system (neural, cardiac, craniofacial, limb, renal, or gastrointestinal). They may occur as isolated defects or as part of a syndrome with other anomalies.

Examples: Neural tube defects (anencephaly, spina bifida); congenital heart malformations (septal defects, outflow tract anomalies); craniofacial malformations (cleft lip/palate); limb anomalies (polydactyly, syndactyly, amelia); renal and urinary tract malformations (renal dysplasia); gastrointestinal tract atresias or stenoses.

Diagnosis and management: Detection commonly occurs prenatally via ultrasound, with confirmation by fetal MRI or genetic testing as indicated. Postnatal assessment follows birth. Management is usually multidisciplinary and may involve surgical correction, medical therapies, and ongoing supportive care. Prognosis varies widely, from conditions compatible with normal life to lifelong disability, depending on the defect's nature and associated anomalies. Prevention strategies include preconception care and targeted measures such as folic acid supplementation to reduce certain neural tube defects.