SCA2 is not a major locus for ADCA type I in French families.
Autosomal dominant cerebellar ataxias (ADCA) of type I, a group of clinically heterogeneous neurodegenerative disorders, are known to be genetically heterogeneous since a second locus for ADCA type I (SCA2) has been identified on the long arm of chromosome 12. Linkage analysis was performed in 7 French ADCA type I families in order to estimate its frequency. We analysed 121 individuals, 39 of whom were affected. In 6 families, the SCA2 candidate interval, spanning 12.8 cM, was excluded by bi- and multipoint analysis. In one family (SAL-315), however, the maximal positive lod score reached 2.03 at the D12S79 locus. A posterior probability of 94% in favor of linkage to SCA2 was calculated by homogeneity analysis. The clinical profile of this family was similar to that of previously described SCA1 and non-SCA1 families, except that dementia was observed in 2 out of 6 patients. This may be a clinical idiosyncrasy in this family and was insufficient for a genotype-phenotype correlation.
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INSERM U289, Hôpital de la Salpêtrière, Paris, France.
Stevanin
G
G
Dürr
A
A
Chneiweiss
H
H
Penet
C
C
Pothin
Y
Y
Agid
Y
Y
Brice
A
A
D000293:Adolescent; D000328:Adult; D002881:Chromosomes, Human, Pair 12; D005190:Family; D005260:Female; D005602:France; D005799:Genes, Dominant; D018740:Genetic Heterogeneity; D008040:Genetic Linkage; D006801:Humans; D008297:Male; D008875:Middle Aged; D013132:Spinocerebellar Degenerations / Q000235:genetics*