A Y-chromosomal haplotype with two short tandem repeat mutations.
Yan Ma1, Jin-Zhi Kuang, Wei Zhu
1Department of Forensic Biology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, 610041 Sichuan, China.
Journal of Forensic Sciences
|April 19, 2012
Summary
A rare Y-chromosome profile with a null allele at DYS448 and an off-ladder allele at DYS456 was identified in a forensic case. These Y-STR variations provided crucial evidence for personal identification.
Area of Science:
- Forensic genetics
- Human genetics
- Molecular biology
Background:
- Y-chromosomal short tandem repeats (STRs) are vital for forensic casework, offering strong exculpatory evidence.
- The 16-locus Yfiler(TM) PCR kit amplifies Y-STRs simultaneously for robust individual identification.
Observation:
- A rare Y-STR profile was detected in a vaginal swab sample from an alleged rape case.
- The profile exhibited a null allele at the DYS448 locus and an off-ladder allele at the DYS456 locus.
Findings:
- Sequence analysis confirmed a true null allele at DYS448 due to repeat deletion and primer binding site mutations.
- The DYS456 locus yielded a small 92-bp fragment (10 repeats), classified as off-ladder.
Implications:
- These Y-STR variations, including null and off-ladder alleles, offer valuable evidence for personal identification in forensic investigations.
- Understanding such rare genetic profiles enhances the accuracy and reliability of Y-STR analysis in legal contexts.
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