title: Linkage disequilibrium at the SCA2 locus.
abstract: Spinocerebellar ataxia type 2 (SCA2) is caused by the expansion of an unstable CAG repeat encoding a polyglutamine tract. Repeats with 32 to 200 CAGs are associated with the disease, whereas normal chromosomes contain 13 to 33 repeats. We tested 220 families of different geographical origins for the SCA2 mutation. Thirty three were positive (15%). Twenty three families with at least two affected subjects were tested for linkage disequilibium (LD) between the SCA2 mutation and three microsatellite markers, two of which (D12S1332-D12S1333) closely flanked the mutation; the other (D12S1672) was intragenic. Many different haplotypes were observed, indicating the occurrence of several ancestral mutations. However, the same haplotype, not observed in controls, was detected in the German, the Serbian, and some of the French families, suggesting a founder effect or recurrent mutations on an at risk haplotype.
authors.affiliation: INSERM U289, Hôpital de la Salpêtrière, Paris, France.
authors.forename: O
authors.initials: O
authors.lastname: Didierjean
authors.forename: G
authors.initials: G
authors.lastname: Cancel
authors.forename: G
authors.initials: G
authors.lastname: Stevanin
authors.forename: A
authors.initials: A
authors.lastname: Dürr
authors.forename: K
authors.initials: K
authors.lastname: Bürk
authors.forename: A
authors.initials: A
authors.lastname: Benomar
authors.forename: A
authors.initials: A
authors.lastname: Lezin
authors.forename: S
authors.initials: S
authors.lastname: Belal
authors.forename: M
authors.initials: M
authors.lastname: Abada-Bendid
authors.forename: T
authors.initials: T
authors.lastname: Klockgether
authors.forename: A
authors.initials: A
authors.lastname: Brice
mesh_terms: D000067528:Ataxins; D018703:Founder Effect; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D009419:Nerve Tissue Proteins; D011506:Proteins / Q000235:genetics*; D013132:Spinocerebellar Degenerations / Q000235:genetics*; D018911:Trinucleotide Repeats / Q000235:genetics
chemical_list: D000067528:Ataxins; D009419:Nerve Tissue Proteins; D011506:Proteins