HLA-B*0749N: the first HLA-B*07 null allele

Area of Science:

• Immunogenetics
• Molecular Biology
• Transplantation Science

Background:

• Accurate human leukocyte antigen (HLA) typing is crucial for successful organ transplantation, minimizing rejection risks.
• The HLA-B locus is a highly polymorphic region, critical for immune response and transplant compatibility.
• Null alleles, which do not produce a functional protein, can complicate HLA matching and impact patient outcomes.

Observation:

• A Polish patient awaiting a kidney allograft presented discrepant results between serological HLA typing (HLA-B "blank") and molecular typing (HLA-B*070201).
• This discrepancy suggested the potential presence of an uncharacterized HLA allele.
• Further investigation was warranted to resolve the typing ambiguity.

Findings:

• The study identified the first documented HLA-B*07 null allele in the Polish population.
• Genomic DNA sequencing revealed a single nucleotide substitution in exon 4 of the HLA-B*07 allele.
• This mutation resulted in a premature stop codon, confirming the allele's null status.

Implications:

• The identification of this HLA-B*07 null allele expands the known spectrum of HLA polymorphism.
• Understanding null alleles is essential for refining HLA typing strategies and improving donor-recipient matching in kidney transplantation.
• This finding may necessitate adjustments in donor screening protocols for populations where this allele is prevalent.