Biomedical subjects
Publications and source records attributed to G T Duncan.
This study demonstrates that the locus D1S80 is highly polymorphic, with 24 different alleles and 66 genotypes in 215 Jordanians. This data set conforms to Hardy-Weinberg expectations(HWE).
The minisatellite locus D1S80, (location: 1p35-p36) GenBank sequence accession # D28507), is a variable number of tandem repeat (VNTR) locus with a 16 base pair repeat size. The sequence of the predominant core repeat region and variants of the D1S80 locus were determined to ascertain whether sequence variation or size variation is the cause of altered migration of some D1S80 alleles. A total of 23 alleles from 14 individuals, previously typed based on the number of repeats (i.e. nominal alleles) for the D1S80 locus, were selected for sequence analysis. The individuals were from African American, Caucasian, and Hispanic databases. From these, 18 different repeat unit sequences were observed and arbitrarily designated A-R. Structural relationships between the alleles became more apparent when the arrays of repeat units were divided into common motifs or super-repeat domains. Six motifs ranging from 3 to 9 repeat units were identified. Several of the alleles included repeat arrays which were too diverse to predict an evolutionary relationship, however, there are two general repeat motif arrays and each has some relationship with either the 18 or the 24 repeat allele. The D1S80 allelic polymorphism is primarily due to variation in the number of repeat units and to sequence variation among repeats, however, it can not be ruled out that some rare alleles may be due to insertions or deletions.
The minisatellite locus D1S80 (1p35-p36), is a highly polymorphic VNTR that also contains a Hinf I polymorphism in the 5' flanking region. Our data suggest that the Hinf I polymorphism is a G > T transversion 58 bases downstream from the forward primer. This G > T transversion also creates a Tsp509 I restriction site. Additionally, a G > C transversion polymorphism was identified in the 3' flanking region by the creation of a BsoF I restriction site immediately adjacent to the repeat region.
There is considerable debate about the methodologies used to estimate VNTR (Variable Number of Tandem Repeats) multi-locus genotype frequencies or odds of inclusion in forensic cases. To compare two of the methods in use, allele frequency distributions among six populations were compared and the effect of population heterogeneity on VNTR multi-locus genotype frequency estimation was examined. Genotype frequencies estimated from single population data were one or two orders of magnitude smaller than those estimated by picking the highest allele frequency in a group of subpopulations to estimate genotype frequencies using a ceiling principle. The average change does not appear to be very sensitive to the set of subpopulations used; four locus frequencies still give inclusion odds of one in a million or less. We think that use of the ceiling principle solves both the statistical problem engendered by subpopulation heterogeneity and the legal problem of assuming that the prepetrator and suspect belong to the same subpopulation. The counterintuitive fact of human genetic polymorphism is that it is easier to identify an individual than it is to identify the subpopulation, ethnic group or race to which that individual belongs.
Using HaeIII as the restriction endonuclease, restriction fragment length polymorphism analysis of dried blood samples from various animals was conducted. Single-locus probes D2S44, D10S28, D1S7, and D4S139, as well as monomorphic probe D7Z2, were used to examine for banding patterns. If bands were present, the samples were further examined for heterogeneity (whether single or multiple bands were observed) and polymorphism (whether variation in band location was shown between the animals studied within a species). Blood samples from animals, including primates, were obtained from Miami Metrozoo, Miami, Florida. Some of the animals were non-related individuals while others were related. Banding patterns were observed in colobus' for D2S44, D1S7, and D4S139; owl monkeys for D2S44; gorillas for D2S44 and D4S139; gibbons for D2S44 and D4S139; siamangs for D2S44, talapoins for DiS7; cranes for D1S7; and otters for D1S7. Based upon these, all of the animals for which a conclusion could be drawn appeared to be homozygous and monomorphic (exhibited only an invariant single band) for the loci examined except colobus' for D4S139, gorillas for D4S139, cranes for D1S7, and otters for D1S7.
The use of sodium thymolphthalein monophosphate for presumptive seminal acid phosphatase testing is discussed. Recent evidence reveals that the dye (o-dianisidine) used in conjunction with alpha-naphthyl phosphate for seminal acid phosphatase testing is a carcinogenic hazard. Numerous tests for seminal acid phosphatase were conducted with swabs from sexual assault kits to compare both substrates. Results of tests using sodium thymolphthalein or alpha-naphthyl phosphate correlated exactly. Sodium thymolphthalein is an effective alternative for preliminary seminal fluid analysis because of its high degree of selectivity and stability, and because it eliminates the potential health hazard.
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