CASE-OF-THE-MONTH - AUGUST 1997 - A 13 YEAR-OLD GIRL WITH PROGRESSIVEMOVEMENT DISORDER

A 13-year-old girl presented with a two year history of declining scho ol performance, loss of coordination, and increased difficulty with sp orts, The family history was positive for Huntington's disease (HD), A n MRI was suggestive for bilateral atrophy of the caudate, HD is autos omal dominant and the HD gene contains a polymorphic trinucleotide (CA G) repeat, which is expanded beyond 36 CAG repeats in HD. This patient had one normal-sized allele and one abnormally expanded allele with 6 8 CAG repeats, confirming the clinical diagnosis of HD. Juvenile onset of HD is uncommon, and is associated with unusually large CAG repeat numbers as was observed in this patient.