Isolation and characterization of novel CAG repeat containing genes expressed in human brain

Neurodegenerative diseases may be caused by expansion of triplet repeats in human genes. To identify novel genes with CAG repeats, we screened a human brain cDNA library with an oligonucleotide probe. Four of the isolated cDNAs were sequenced, analyzed for polymorphisms, chromosomal localization, evolutionary conservation and expression. One of the repeats is bi-allelic with 10 triplets (80% of chromosomes) and 7 triplets (20% of chromosomes). In one of the genes two CAG repeats coding for 10 and 17 glutamines are localized in the same reading frame.