IDENTIFICATION AND CHROMOSOMAL LOCALIZATION OF HUMAN GENES CONTAININGCAG CTG REPEATS EXPRESSED IN TESTIS AND BRAIN/

Human genes containing triplet repeats have been demonstrated to be in volved in several neurodegenerative diseases by expansion of the repea t in succeeding generations. To identify novel genes involved in such pathologies, we have isolated transcripts containing (CAG/CTG)(n) repe ats using two approaches. First, we screened 4 x 10(6) clones represen ting 10 copies of a human testis cDNA library using a (CAG)(14) oligon ucleotide probe. Among the 910 clones identified, the 243 clones with the strongest hybridization signal were sequenced partially from 3' or 5' ends. This provided us with 251 partial sequences that grouped int o clusters corresponding to 39 genes, of which 19 represent unknown sp ecies. Second, we selected 203 additional ESTs containing (CAG/CTG)(n) repeats representing 121 clusters from the IMAGE consortium infant br ain cDNA library. From these two series of sequences, we have localize d 95 genes on human chromosomes using a panel of whole genome radiatio n hybrid (Genebridge 4). These genes are located on all of the chromos omes except for chromosome X, the highest density being observed on ch romosome 19.