Late-onset SCA2: 33 CAG repeats are sufficient to cause disease.
SCA-2 is an autosomal dominant inherited disorder characterized by ataxia, slow saccades, and hyporeflexia. The authors evaluated a patient with a mild balance problem with a SCA-2 allele sized at 33 CAG repeats. The authors then ascertained her 91 year-old mother, who showed disease onset at age 86 with an SCA-2 allele of identical size. Their study indicates that 33 CAG repeats can be pathogenic at the SCA-2 locus, though such an allele may produce an extremely late onset and gradual rate of disease progression.
Fernandez
M
M
Division of Medical Genetics, University of Washington Medical Center, Seattle, 98195-7110, USA.
McClain
M E
ME
Martinez
R A
RA
Snow
K
K
Lipe
H
H
Ravits
J
J
Bird
T D
TD
La Spada
A R
AR
D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000473:pathology; D018450:Disease Progression; D019075:Electrophoresis, Capillary; D005260:Female; D005799:Genes, Dominant; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010375:Pedigree; D010641:Phenotype; D016133:Polymerase Chain Reaction; D020754:Spinocerebellar Ataxias / Q000175:diagnosis* / Q000209:etiology / Q000235:genetics*; D014057:Tomography, X-Ray Computed; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*