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 p redictive testing, underwent neurological assessment before their gene stat us had been determined, The association between pre-gene result symptoms an d 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. Af ter exclusions, 61% of gene-positive patients had minor neurological signs, whereas only 8% testing gene negative had signs, Minimal chorea observed i n 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 s tatus, but behavioural and cognitive symptoms were more often reported by t he gene-positive group. Although an 'at-risk' individual may receive a gene -positive result, neurological examination remains the most accessible, rel iable and cost effective means of determining clinical disease onset. (C) 2 000 Harcourt Publishers Ltd.