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Sequence differences between HLA-B and TNF distinguish different MHC ancestral haplotypes.
L J Abraham1, C Leelayuwat, G Grimsley
1Department of Clinical Immunology, Royal Perth Hospital, Western Australia.
Tissue Antigens
|March 1, 1992
Summary
Genetic analysis reveals that the CL region near HLA-B exhibits high allelic variation due to duplicated geometric elements. These elements create unique, haplospecific patterns, enabling accurate typing of ancestral haplotypes.
Area of Science:
- Genetics
- Molecular Biology
- Immunogenetics
Background:
- The HLA-B locus is known for its extreme polymorphism.
- Previous RFLP analysis indicated high allelic variation in the telomeric CL region of HLA-B.
Purpose of the Study:
- To sequence the CL region telomeric to HLA-B and characterize its allelic variation.
- To investigate the role of duplicated geometric elements in polymorphism within the CL region.
- To develop a method for typing ancestral haplotypes based on CL region sequence variation.
Main Methods:
- DNA sequencing of the CL region in specific ancestral haplotypes.
- Polymerase chain reaction (PCR) amplification of geometric elements.
- Gel electrophoresis to analyze PCR products and generate CL patterns.
Main Results:
- Polymorphism in the CL region is attributed to sequence variations in duplicated geometric elements.
- Element lengths vary within and between haplotypes due to insertions and deletions.
- PCR amplification yields characteristic gel patterns (CL patterns) for different ancestral haplotypes.
- The majority of CL patterns are haplospecific, uniquely identifying ancestral haplotypes.
- At least 12 distinct allelic patterns were identified in 29 cell lines representing 16 ancestral haplotypes.
Conclusions:
- CL region patterns are haplospecific, confirming conserved chromosomal segments in ancestral haplotypes.
- This haplotypic nature indicates sequences are identical by descent.
- The CL region and its geometric elements provide a valuable tool for typing ancestral haplotypes.