Forensic issues in Down syndrome fatalities.

Down syndrome, or trisomy 21, is the most common chromosomal abnormality associated with intellectual impairment. Premature death is a feature of the syndrome due to a wide variety of conditions including congenital heart disease, impaired immune responses resulting in respiratory infections, acute leukaemia, upper airway narrowing, pulmonary hypertension, Alzheimer disease and atlantoaxial instability. Cases of Down syndrome not uncommonly present for medicolegal autopsy, as the non-specificity of symptoms and signs often precludes accurate antemortem establishment of a cause of death. Manifestations of Down syndrome are reviewed with an analysis of possible mechanisms of death and findings at autopsy.