Complex origin of the HLA-DR10 haplotype

Area of Science:

• Immunogenetics
• Molecular Evolution
• Primate Genetics

Background:

• The human leukocyte antigen (HLA) complex, particularly the DRB gene region, exhibits significant evolutionary rearrangements in primates.
• These rearrangements have led to diverse haplotypes with varying DRB gene content and structure.

Purpose of the Study:

• To investigate the evolutionary origins and composition of the DR10 haplotype within the HLA complex.
• To assess the implications of DR10 haplotype structure on its classification and understanding of DRB gene diversity.

Main Methods:

• Selective intron sequencing was employed to analyze the DR10 haplotype.
• Comparative analysis of gene segments and evolutionary divergence times was performed.

Main Results:

• The DR10 haplotype is a mosaic of at least three distinct segments of different evolutionary origins.
• Specific segments are derived from DRB1*03-like and DR1-like haplotypes, with a core segment diverging ~30 million years ago.
• The DR10 haplotype carries three DRB genes/fragments: DRB1*10, DRB6, and DRB9.

Conclusions:

• The complex mosaic structure of the DR10 haplotype challenges its current classification within the DR1 group.
• HLA-DRB gene rearrangements are a key mechanism driving diversity at DRB loci.
• The DRB region shows localized instability flanked by conserved evolutionary regions.