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The SCA12 Mutation as a Rare Cause of Spinocerebellar Ataxia
Jeremy A. Cholfin, BS;
María-Jesús Sobrido, MD, PhD;
Susan Perlman, MD;
Stefan M. Pulst, MD;
Daniel H. Geschwind, MD, PhD
Arch Neurol. 2001;58:1833-1835.
Background Spinocerebellar ataxias are a group of
phenotypically and genetically heterogeneous disorders characterized by
progressive degeneration of the cerebellum. The expansion of a CAG
repeat upstream of the PP2APR55ß gene has been recently
reported as a novel cause of a dominantly inherited ataxia (SCA12) in a
kindred with limb tremor as an early feature.
Objective To explore the relative frequency of SCA12
among familial and sporadic spinocerebellar ataxias in an ethnically
diverse patient population.
Methods We used polymerase chain reaction to analyze
CAG repeat size in a series of patients presenting to an ataxia clinic
in California.
Results The SCA12 expansion was not detected in any of the
cases investigated. The largest allele found had 22 repeats, a finding
within the proposed nonpathogenic range. Distribution of repeat size
and heterozygosity were similar to that described previously.
Conclusions These results, coupled with findings in
other populations, indicate that the SCA12 mutation is a rare cause of
spinocerebellar degeneration. Diagnostic testing for SCA12 should be
considered in patients with cerebellum disorders and an atypical
clinical phenotype, especially when tremor is initially present.
From the Neurogenetics Program, Department of
Neurology, University of California, Los Angeles School of Medicine (Mr
Cholfin and Drs Sobrido, Perlman, and Geschwind), and Division of
Neurology, Cedars-Sinai Medical Center, Los Angeles (Dr Pulst).
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