Huntington's disease CAG trinucleotide repeats in pathologically confirmed post-mortem brains.

CAG repeat expansion in the Huntington's disease gene (HD) was examined in postmortem brains from 310 clinically diagnosed and 15 'at risk' individuals. Presence of an expanded CAG allele (>37 units) was the cause of the disorder in almost all cases (307 of 310). Despite a diversity of reporting clinicians, neurological and psychiatric onset and age at death all displayed significant inverse correlations with CAG number indicating that diagnosis of onset is reasonably accurate, and that most patients die from the disease and its complications.