HGM2002 Poster Abstracts: 11. Genome Diversity
POSTER NO: 554
Sequencing and typing of the Y-specific minisatellite MSY1(DYF155S1) by fluorescence detection
Yu Lei, Wu Xinyao, Cai Gueiqing
The human Y chromosome is paternally inherited and in a haplotype model. These features make the polymorphism study of Y chromosome very useful in different fields of science, including the study and inference of population genetics, forensic applications and paternity analysis. The human Y-specific minisatellite MSY1(DYF155S1) locus has been reported to be the most variable locus on the Y by far. To study the polymorphisms of MSY1 locus and its applications to forensic science, the allele length variation from 155 unrelated males in Chinese Han population was studied by using amplified fragment length polymorphism (Amp-FLP) method. The sizes of the alleles of MSY1 locus are between 1500-2500bp. Ten alleles selected were sequenced from 5'- and 3'- ends by Cycle Sequencing on ABI PrismTM 377 Sequencer. Four types of variant repeats were identified, including three types, designated Type 1, 3 and 4, was reported before. The only one new type of variant repeat, which begins the array in one male, differs from a Type 3 repeat by a T/A transversion at position 21. Ten alleles sequenced had the same modular structure, starting with a repeat block of Type 3 followed by a block of Type 1 before the central block of Type 3 at 5'end, and starting with a repeat block of Type 4 followed by the central repeat block of Type 3 at 3' end. To reveal the diversity of MSY1 lous in Chinese Han population, one forward typing detecting type 1 variant was performed using the repeat specific primer labeled with a fluorescence dye in the 5' end. The MVR-PCR products were separated and typed using an ABI PrismTM 377 Sequencer and Genescan analysis software. Most of the 155 samples displayed continuous bands which differ 25bp among them. Out of the 155 samples, 34 samples did not display continuous bands, they had one or two bands lost. It was demonstrated by sequencing that the lost bands had type 3 repeats. The polymorphisms at MSY1 locus in Chinese individuals by using this method showed difference in the size of first fragment and the total numbers of fragments. In the 155 samples 76 different haplotypes were encountered, of which 47 were observed once only. Sorting the alleles by using both Amp-FLP and MVR-PCR methods, there were 121 different haplotypes. For forensic application, we also performed the sensitivity study and male/female or female/female DNA mixtures study. Our results indicate that Y-specific MSY1 detected by using Amp-FLP and MVR-PCR methods will be useful in forensic science such as identification of male DNA in case with male/female stain mixtures and paternity testing, especially for deficiency cases where the alleged father is not available.
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