GENETIC TESTING OF CHILDREN AT RISK FOR HUNTINGTONS-DISEASE

We reviewed 44 symptomatic children tested for CAG repeat expansions i n the gene responsible for Huntington's disease (HD). Thirty-three pat ients had CAG repeat expansions, and 11 did not. No patient with a CAG repeat expansion had a negative family history of HD. Of the 15 patie nts presenting in the first decade, 12 had greater than 80 CAG repeats and a clinical profile at the time of the test that included two or m ore of the following: declining school performance, seizures, oral mot or dysfunction, rigidity, and gait disorder. Three patients with small er CAG repeat expansions had incomplete or atypical symptom profiles. Symptom patterns in patients presenting in the second decade were more varied but usually included behavioral and motor symptoms. Patients w ithout CAG expansions had incomplete or atypical symptom profiles. We define the historical and clinical profiles of HD presenting in the fi rst two decades and suggest that physicians exercise restraint in usin g a ''diagnostic'' gene test for ED in the evaluation of at-risk child ren with incomplete or atypical symptom profiles or no family history of HD, in whom test results are very likely to be normal or unrelated to the patient's symptoms.