Cloning of the gene for spinocerebellar ataxia 2 reveals a locus with high sensitivity to expanded CAG/glutamine repeats.
Two forms of the neurodegenerative disorder spinocerebellar ataxia are known to be caused by the expansion of a CAG (polyglutamine) trinucleotide repeat. By screening cDNA expression libraries, using an antibody specific for polyglutamine repeats, we identified six novel genes containing CAG stretches. One of them is mutated in patients with spinocerebellar ataxia linked to chromosome 12q (SCA2). This gene shows ubiquitous expression and encodes a protein of unknown function. Normal SCA2 alleles (17 to 29 CAG repeats) contain one to three CAAs in the repeat. Mutated alleles (37 to 50 repeats) appear particularly unstable, upon both paternal and maternal transmissions. The sequence of three of them revealed pure CAG stretches. The steep inverse correlation between age of onset and CAG number suggests a higher sensitivity to polyglutamine length than in the other polyglutamine expansion diseases.
Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS, INSERM, ULP, B.P., Illkirch, Strasbourg, France.
G
G
Imbert
F
F
Saudou
G
G
Yvert
D
D
Devys
Y
Y
Trottier
J M
JM
Garnier
C
C
Weber
J L
JL
Mandel
G
G
Cancel
N
N
Abbas
A
A
Dürr
O
O
Didierjean
G
G
Stevanin
Y
Y
Agid
A
A
Brice
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000483:Alleles; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D000067528:Ataxins; D001483:Base Sequence; D002648:Child; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D011506:Proteins / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D013132:Spinocerebellar Degenerations / Q000235:genetics*; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology; D018911:Trinucleotide Repeats
D000911:Antibodies, Monoclonal; D000067528:Ataxins; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D035181:TATA-Box Binding Protein; D014157:Transcription Factors