Huntington's disease: neurological assessment of potential gene carriers presenting for predictive DNA testing.
One hundred and fifty-six potential gene carriers who were 50% 'at risk' of inheriting the Huntington's disease (HD) mutation, and who presented for predictive testing, underwent neurological assessment before their gene status had been determined. The association between pre-gene result symptoms and minimal neurological signs (insufficient for diagnosis in their own right) and subsequent gene status was determined. Of these, 38% tested positive for the HD mutation. Fifty-one individuals had minor neurological signs. After exclusions, 61% of gene-positive patients had minor neurological signs, whereas only 8% testing gene negative had signs. Minimal chorea observed in the toes and feet with the subject supine, and the patient being stressed by a mental task carried 96% specificity and 86% positive predictive value for gene-positive status. Neurological symptoms did not distinguish gene status, but behavioural and cognitive symptoms were more often reported by the gene-positive group. Although an 'at-risk' individual may receive a gene-positive result, neurological examination remains the most accessible, reliable and cost effective means of determining clinical disease onset.
McCusker
E
E
Department of Neurology, Westmead Hospital, Australia.
Richards
F
F
Sillence
D
D
Wilson
M
M
Trent
R J
RJ
D000328:Adult; D004252:DNA Mutational Analysis; D005260:Female; D006580:Genetic Carrier Screening; D006801:Humans; D006816:Huntington Disease / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination