title: D20S16 is a complex interspersed repeated sequence: genetic and physical analysis of the locus.
abstract: The genomic structure of the D20S16 locus has been evaluated using genetic and physical methods. D20S16, originally detected with the probe CRI-L1214, is a highly informative, complex restriction fragment length polymorphism consisting of two separate allelic systems. The allelic systems have the characteristics of conventional VNTR polymorphisms and are separated by recombination (theta = 0.02, Zmax = 74.82), as demonstrated in family studies. Most of these recombination events are meiotic crossovers and are maternal in origin, but two, including deletion of the locus in a cell line from a CEPH family member, occur without evidence for exchange of flanking markers. DNA sequence analysis suggests that the basis of the polymorphism is variable numbers of a 98-bp sequence tandemly repeated with 87 to 90% sequence similarity between repeats. The 98-bp repeat is a dimer of 49 bp sequence with 45 to 98% identity between the elements. In addition, nonpolymorphic genomic sequences adjacent to the polymorphic 98-bp repeat tracts are also repeated but are not polymorphic, i.e., show no individual to individual variation. Restriction enzyme mapping of cosmids containing the CRI-L1214 sequence suggests that there are multiple interspersed repeats of the CRI-L1214 sequence on chromosome 20. The results of dual-color fluorescence in situ hybridization experiments with interphase nuclei are also consistent with multiple repeats of an interspersed sequence on chromosome 20.
authors.affiliation: Department of Biochemistry, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Bowden
authors.forename: M D
authors.initials: MD
authors.lastname: Krawchuk
authors.forename: E J
authors.initials: EJ
authors.lastname: Weaver
authors.forename: T D
authors.initials: TD
authors.lastname: Howard
authors.forename: R G
authors.initials: RG
authors.lastname: Knowlton
authors.forename: P N
authors.initials: PN
authors.lastname: Rao
authors.forename: M J
authors.initials: MJ
authors.lastname: Pettenati
authors.forename: R
authors.initials: R
authors.lastname: Hayworth
authors.forename: B J
authors.initials: BJ
authors.lastname: Wagner
authors.forename: C B
authors.initials: CB
authors.lastname: Rothschild
mesh_terms: D000483:Alleles; D001483:Base Sequence; D016384:Consensus Sequence; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D010375:Pedigree; D012150:Polymorphism, Restriction Fragment Length; D011995:Recombination, Genetic; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
chemical_list: D005819:Genetic Markers