Related Experiment Videos
DQB1 promoter sequence variability and linkage in caucasoids
S Reichstetter1, G Brünnler, J R Kalden
1Department of Medicine III, University of Erlangen-Nürnberg, Germany.
Human Immunology
|December 1, 1996
Summary
Sequence variability in HLA-DQB1 upstream regulatory regions (URR) is linked to the DQB1 gene structure. This linkage, known as linkage disequilibrium, is tight but shows exceptions for DQB1 DQ5 and DQ6 haplotypes.
Area of Science:
- Immunogenetics
- Molecular Biology
- Population Genetics
Background:
- Human Leukocyte Antigen (HLA) class II genes exhibit diversity through sequence variability in their upstream regulatory regions (URR).
- Twelve upstream regulatory region (URR) variants for HLA-DQB1 were previously identified in the region upstream of the DQB1 gene's first exon.
Purpose of the Study:
- To investigate the distribution of HLA-DQB1 promoter alleles (QBP1) in a population.
- To determine the linkage disequilibrium between these promoter alleles and the structural DQB1 gene variants.
Main Methods:
- Developed 25 sequence-specific oligonucleotide probes and one primer pair to identify all 12 known QBP1 alleles.
- Analyzed DNA from 215 healthy, unrelated German individuals for DQB1 and QBP1 allele distribution and linkage.
Main Results:
- Ten of the 12 known QBP1 alleles were observed in the study population.
- A strong linkage disequilibrium was found between HLA-DQB1 promoter and coding regions, with promoter allele frequencies largely mirroring those of their linked DQB1 alleles.
- Exceptions to tight linkage were noted for DQB1 DQ5 and DQ6 haplotypes, where DQB1 alleles could associate with different, albeit related, QBP1 alleles.
Conclusions:
- Promoter and coding region variability in HLA-DQB1 are tightly linked by linkage disequilibrium, with notable exceptions for DQB1 DQ5 and DQ6.
- The strong linkage suggests functional importance for maintaining haplotypic integrity, given known functional differences between QBP1 alleles.