Lezin A, Cancel G, Stevanin G, Smadja D, Vernant JC, Dürr A, Martial J, Buisson GG, Bellance R, Chneiweiss H, Agid Y, Brice A. Autosomal dominant cerebellar ataxia type I in Martinique (French West Indies): genetic analysis of three unrelated SCA2 families.
Hum Genet 1996;
97:671-6. [PMID:
8655151 DOI:
10.1007/bf02281881]
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Abstract
Autosomal dominant cerebellar ataxias (ADCAs) are a group of neurodegenerative disorders that are clinically and genetically heterogeneous. We report here a genetic linkage study, with five chromosome 12q markers, of three Martinican families with ADCA type 1, for which the spinocerebellar ataxia 1 (SCA1) locus was excluded. Linkage to the SCA2 locus was demonstrated with a maximal lead score of 6.64 at theta = 0.00 with marker D12S354. Recombinational events observed by haplotype reconstruction demonstrated that the SCA2 locus is located in an approximately 7-cM interval flanked by D12S105 and D12S79. Using the z(max)-1 method, multipoint analysis further reduced the candidate interval for SCA2 to a region of 5 cM. Two families shared a common haplotype at loci spanning 7 cM, which suggests a founder effect, whereas a different haplotype segregated with the disease in the third family. Finally, a mean anticipation of 12+/-14 years was found in parent-child couples, with no parental sex effect, suggesting that the disease might be caused by an expanded and unstable triplet repeat.
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