Full-length HLA-DRB1 coding sequences generated by a hemizygous RNA-SBT approach

Area of Science:

• Immunogenetics
• Molecular Biology
• Human Leukocyte Antigen (HLA) research

Background:

• Over 90% of known HLA-DRB1 alleles have incomplete sequences, hindering functional polymorphism analysis beyond exon 2.
• Polymorphism exists across all HLA-DRB1 exons, but its full extent is often uncharacterized due to sequence gaps.

Purpose of the Study:

• To develop and validate a novel RNA sequence-based typing (SBT) approach for obtaining full-length HLA-DRB1 coding sequences.
• To accurately define the polymorphic content of HLA-DRB1 alleles, including those with previously incomplete sequences.

Main Methods:

• A hemizygous, full-length RNA sequencing approach using group-specific HLA-DRB1 amplification and sequencing.
• Utilized short amplicon lengths (801 bp) for efficient RNA full-length sequence access.
• Validated the RNA-SBT approach on known DRB1 alleles and applied it to alleles with incomplete sequences.

Main Results:

• Successfully generated full-length coding sequences for 54 previously incompletely sequenced HLA-DRB1 alleles.
• Identified one novel and corrected one existing HLA-DRB1 allele using the RNA-SBT method.
• Demonstrated the universal applicability of RNA-based sequencing for HLA-DRB1 characterization.

Conclusions:

• The RNA-SBT approach provides a universal and efficient method for obtaining complete HLA-DRB1 coding sequences.
• This technique enhances the understanding of HLA-DRB1 polymorphism, crucial for immunological and clinical applications.
• The method facilitates the identification of new alleles and correction of existing ones, improving HLA database accuracy.