A 37-YEAR-OLD woman presented with a 6-month history of progressive gait difficulty and dysarthria. She stated that her only child, a 13-year-old daughter, was "clumsy," but she was unaware of other family members with the same problem. Examination was noteworthy for mild dysarthria, slowing of saccades and gaze-holding difficulty, diffuse hyporeflexia, mild dysmetria and dysdiadochokinesis, and gait ataxia. The patient's daughter had similar findings but was areflexic. A head computed tomographic scan (Figure 1 ) showed impressive pontocerebellar atrophy, also readily evident on magnetic resonance imaging (Figure 2). Serologic testing revealed that the CAG repeat lengths of the alleles for the ataxin-2 gene were 41/22 in the patient, 51/22 in her daughter, and 22/22 (homozygous) in the patient's unaffected mother (normal repeat length, 14-31). This expanded polyglutamine tract was diagnostic for spinocerebellar ataxia type 2.
Silverman IE. Spinocerebellar Ataxia Type 2. Arch Neurol. 1999;56(5):628. doi:10.1001/archneur.56.5.628