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Analysis of mutational changes at the HLA locus in single human sperm
M M Huang1, H A Erlich, M F Goodman
1Molecular Biology Program, University of Southern California, Los Angeles 90089-1340, USA.
Human Mutation
|January 1, 1995
Summary
This study investigated HLA-DPB1 gene mutations using single sperm PCR, revealing potential microgene conversion and unrepaired DNA. These findings may explain human leukocyte antigen (HLA) diversity and mosaicism from incomplete DNA repair during gametogenesis.
Area of Science:
- Genetics
- Molecular Biology
- Immunogenetics
Background:
- The Human Leukocyte Antigen (HLA) system, particularly the HLA-DPB1 locus, is highly polymorphic.
- Understanding the mechanisms generating allelic diversity is crucial for immunology and transplantation.
- Sperm typing offers a unique window into meiotic recombination and mutation processes.
Purpose of the Study:
- To screen for mutations in the HLA-DPB1 gene using single sperm analysis.
- To investigate potential mechanisms contributing to novel allele formation and allelic diversity.
- To explore the role of DNA repair processes during gametogenesis.
Main Methods:
- Employed a single sperm polymerase chain reaction (PCR) and direct sequencing technique.
- Analyzed over 800 single sperm from an individual heterozygous for HLA-DPB1.
- Included control experiments with sperm from homozygous individuals.
Main Results:
- Identified 16 nucleotide sequence differences across six polymorphic regions between the two alleles.
- Detected a potential microgene conversion event.
- Observed unrepaired heteroduplex DNA in three instances, resembling postmeiotic segregation events.
- Noted unusual sperm characteristics in control experiments.
Conclusions:
- The study suggests that incomplete DNA mismatch repair during gametogenesis could be a source of mosaicism.
- The findings provide insights into the generation of allelic diversity within the Major Histocompatibility Complex (MHC).
- Single sperm analysis is a viable method for studying genetic variation and mutation at highly polymorphic loci.