ISOLATION AND MAPPING OF 3 NEW POLYMORPHIC MARKERS TO CHROMOSOME-3, CHROMOSOME-20 AND CHROMOSOME-21

Screening of single human chromosome plasmid libraries using a digoxyg enin labelled (AAAT)(15) oligonucleotide probe led to the identificati on of several positive clones. DNA sequence analysis of these was carr ied out and showed the presence of a number of simple DNA repeats. Oli gonucleotide primers were designed from the sequences flanking these r epeats and tested in PCR amplification reactions of human genomic DNA. Three of the markers tested were shown to be polymorphic with heteroz ygosities ranging from 40% to 69%. The markers were assigned to chromo somes using a panel of monochromosomal somatic cell hybrids combined w ith linkage analysis using DNA from the CEPH panel of families. The ma rkers designated (AAAT)(11), (AAAT)(12) and (CA)(19) were thus assigne d to chromosomes 3, 21 and 20 respectively.