Spinocerebellar ataxia type 12 is rare in the United Kingdom.

Abstract

The spinocerebellar ataxias constitute a heterogeneous group of neurologic conditions characterized by cerebellar ataxia and other neurologic features. Thirteen loci (SCA 1 to 8, SCA 10 to 14) have been identified, including mutations in seven genes. SCA-12 on chromosome 5q31-33 is the most recently identified gene.1 Affected subjects have expansions containing 66 to 78 CAG repeats in the presumed 5’-untranslated region of this gene, which encodes the subunit of the serine/threonine protein phosphatase PP2A, whereas controls have 7 to 28 repeats. To establish the frequency of the SCA-12 expansion in the United Kingdom, we screened DNA samples from patients with ataxia in our database. Three hundred and ninety-two participants with unrelated index cases of cerebellar ataxia were screened for the SCA-12 mutation. Participants were recruited from a variety of sources, including local and nationwide referral. Expansions in the known SCA genes and the Friedreich gene were excluded. Of the 392 cases, 99 had features consistent with dominantly inherited ataxia (ADCA), and 132 had idiopathic late-onset cerebellar ataxia (ILOCA, i.e., relatively uncomplicated cerebellar ataxia without a family history). An additional …