Hybridization of probe pDPl51 (locus D15S2) to genomic human DNAs digested with EcolU revealed allelic restriction fragments 9 and 11 kilobase-pairs (kb) in length. Hybridization of pDP151 to EcoRI-digested DNAs from 21 Chinese hamster X human hybrid cell clones containing different subsets of human chromosomes demonstrated cosegregation of the 9 and 11 kb EcoRI fragments with human chromosome 15. DI5S2 and two other polymorphic loci previously mapped to chromosome 15-Dl5SI and DISSbwere localized to specific regions on human chromosome 15. Eight Chinese hamster X human somatic cell hybrid clones derived from a human donor heterozygous for a balanced translocation between chromosomes 15 and 22 [t( 15;22)(q14;q13.3); Oliver et al, Cytogenet Cell Genet 22503-510, 19781 were studied. After digestion of human and hybrid DNAs with HindIIl and Southern blotting, pDP151 (D15S2) and pMS1-14 (D15S1)
hybridized to fragments of 4 and 4.5 kb, respectively. Further, pMS1-14 (D15S1) and p9-la (D15S6) hybridized to EcoRI fragments of 3.5 and 3.2 kb. All fragments cosegregated with the der(22) derivative chromosome containing region 15q14415qter. In situ hybridization of these probes to normal human chromosomes mapped the corresponding loci with greater precision: D15SI to 15q15-+ 15q21, D15S2 to 15q15-15q22, and D15S6to 15q22-15q24.