Different ancestor alleles: a reason for the bimodal fragment size distribution in the minisatellite D2S44 (YNH24)

Three conserved repeat order motifs found in the D2S44 (YNH24) minisatellit e by minisatellite variant repeat mapping by PCR (MVR-PCR) might be the rem nants of three different ancestor alleles. One of the motifs is found in th e group of alleles around the 2.8 kbp fragment size and the two others in t he group of alleles around the 4.1 kbp fragment size in the bimodal frequen cy distribution of HinfI fragments characteristic for the D2S44 minisatelli te. The conserved repeat-order motifs were found at the 3'-end of the allel es, whilst the 5'-end was highly polymorphic. This is the first time a mini satellite is shown to have repeat-order motifs that are associated with fra gment length. These results were obtained by MVR-PCR mapping of 49 alleles with primers specific for the core nucleotide sequence variation ...(G)(5)T GPT, ...(G)(4)TGTT or ...(G)(4)TGTT.