Somatic mosaicism for Friedreich's ataxia GAA triplet repeat expansions in the central nervous system.
Most patients with Friedreich's ataxia (FRDA) carry expanded GAA repeats in both homologues of the frataxin gene on chromosome 9. We determined the size of the GAA repeats in autopsied samples from the CNS of six FRDA patients. We observed heterogeneity of repeat sizes in different CNS regions, indicative of extensive mitotic instability. Samples from the same CNS subdivision (e.g., cortex, thalamus) contained a similar mixture of alleles, suggesting that the pattern of repeat size mosaicism reflects the developmental history of each sample. Regional differences in repeat size could not account for the characteristic distribution of pathology in FRDA, which appears instead to be related to the pattern of frataxin expression.
Montermini
L
L
Centre de Recherche Louis-Charles Simard, Montréal, Québec, Canada.
Kish
S J
SJ
Jiralerspong
S
S
Lamarche
J B
JB
Pandolfo
M
M
D000328:Adult; D002490:Central Nervous System / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005621:Friedreich Ataxia / Q000235:genetics* / Q000473:pathology; D005796:Genes; D006801:Humans; D033862:Iron-Binding Proteins; D009030:Mosaicism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D000096923:Frataxin
D033862:Iron-Binding Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D000096923:Frataxin