Mapping of the gene for a novel spinocerebellar ataxia with pure cerebellar signs and epilepsy

Abstract

We investigated a family with a new type of autosomal dominant cerebellar ataxia (ADCA) in which pure cerebellar ataxia is often accompanied with epilepsy. No CAG repeat expansions were detected at the spinocerebellar ataxia (SCA) type 1, 2, 3, 6, or 7 locus, and SCAs 4 and 5 were excluded by linkage analysis. We found linkage between the disease locus and D22S274 (Zmax = 3.86 at θ = 0.00) and two other makers in 22q13‐qter. Haplotype analysis of the crossover events and the multipoint linkage mapping localized the disease locus to an 8.8‐cM region between D22S1177 and D22S1160. Ann Neurol 1999;45:407–411

Spinocerebellar ataxias

“…As a general rule, there is an inverse correlation between age at onset of SCA 10 and the size of the ATTCT repeat expansion [33][34][35] .…”

“…The disease-causing mutation that leads to SCA 10 is a large expansion of a pentanucleotide (ATTCT) repeat located in an intron of a gene of unknown function (SCA 10) on chromosome 22q 16,[31][32][33][34] .…”

“…The size of the expanded alleles range from 800 to 4500 ATTCT repeats for a diagnosis of SCA 10 [33][34][35] .…”

The history of spinocerebellar ataxia type 10 in Brazil: travels of a gene

“…SCA type 10 was originally identifi ed only in Mexican familes and had a phenotype characterized by a combination of cerebellar ataxia and epilepsy [5][6][7][8][9] .…”

“…In 1999, the locus of this new form of SCA was mapped independently by Zu et al 7 and Matsuura et al 8 ra et al, leaded by Tetsuo Ashisawa, Houston, Texas, defi ned that the ancesters of two families studied by the two groups were from the same region of Mexico, suggesting a common ancestry 7,8 . In 2000, the Houston group, in collaboration with the Los Angeles group, discovered the genetic mutation causing SCA type 10; a large pentanucleotide (ATTCT) expansion located in intron 9 of the SCA type 10 gene 13 .…”