Molecular analysis of HPRT1(+) somatic cell hybrids derived from a carrierof an HPRT1 mutation responsible for Lesch-Nyhan syndrome

Heterozygous carriers of HPRT1 mutations responsible for Lesch-Nyhan syndro me can be detected by analysis of somatic cell hybrids derived from periphe ral blood lymphocytes and Hprt1-negative cells of rodent origin followed by selection in culture medium containing hypoxanthine, aminopterine, and thy midine (HAT). The parental origin of the X chromosome containing the normal HPRT1 allele in HPRT1(+) hybrid cell lines can be determined by molecular haplotyping attributable to highly polymorphic X-linked markers. We used th is procedure to study a presumed carrier whose paternal active X chromosome always segregated in the cell hybrids derived from her. Conversely, her ma ternal X chromosome was systematically absent in most cell hybrids, or when present, it was inactive and coexisted with an active, paternal X chromoso me. These results clearly demonstrated that the proband was a heterozygous carrier of a mutation responsible for HPRT1 deficiency. (C) 2001 Wiley-Liss , Inc.