GERMINAL HPRT SPLICE DONOR SITE MUTATION RESULTS IN MULTIPLE RNA SPLICING PRODUCTS IN T-LYMPHOCYTE CULTURES

We have used peripheral blood T-lymphocyte cultures to analyze the hpr t mutation in two Lesch-Nylan syndrome males who are cousins and to co nfirm the carrier status of female members of the family. Both cDNA an d genomic DNA sequencing studies show that this patient carries a hith erto undescribed single base deletion in the exon 5 donor splice site sequence (15: +/- 1, Delta G, base number 31635), The largest cDNA pro duct contained all nine hprt exons plus an insertion of 66 bases of in tron 5, consistent with the use of a cryptic splice site in intron 5 ( aag(67)/gtaagc). This splicing error would result in a chain terminati ng codon immediately after exon 5 (15:2-4, taa) and predicts a polypep tide of 133 amino acids, This loss of the normal splice donor site als o results in multiple hprt mRNA species, combining the use of the cryp tic splice site in intron 5 and splicing errors involving exons 2-6. I n addition to defining a new Lesch-Nylan mutation (hpTt(Henryville)), these results provide insight into aberrant splicing of hprt mRNA in T -lymphocytes.