Five polymorphic microsatellite VNTRs on the human X chromosome.

摘要: The human genome contains approximately 50,000 copies of an interspersed repeat with the sequence (dT.dG/dA.dC)n, where n = 10-60. We and others have found that several these repeats variable lengths in different individuals, allelic fragments varying size by multiples 2 bp. These "microsatellite" number tandem (VNTRs) may be scored PCR, using unique flanking primers to amplify repeat-containing regions resolving products on DNA sequencing gels. Since few VNTRs been X chromosome, we screened a flow-sorted chromosome-specific genomic library for microsatellites. Approximately 25% phage clones hybridized poly (dT-dG).poly(dA-dC) probe. Of seven X-linked microsatellites present positive phages, five are polymorphic three both eight or more alleles heterozygosities exceeding 75%. Using PCR DNAs from hybrid cell panels, confirmed localization regionally mapped four them. fifth VNTR was virtue its tight linkage DXS87 Centre du Polymorphisme Humain families. conclude whatever factors limit occurrence "classical" RFLPs chromosome do not appear operate case microsatellite VNTRs.