A DNA-based detection and screening system for identifying HLA class I expression variants by sequence-specific...

Area of Science:

• Immunogenetics
• Molecular Biology
• Transplantation

Background:

• Molecular methods have largely replaced serological techniques for Human Leukocyte Antigen (HLA) typing.
• Reliance on existing sequence data in molecular typing can miss unsequenced or low-expression HLA variants, termed null alleles.
• Failure to identify null alleles poses risks for allogeneic transplantation outcomes.

Purpose of the Study:

• To develop a molecular method capable of detecting known and novel Human Leukocyte Antigen (HLA) class I expression variants.
• To investigate mutations, particularly in cytosine-rich regions, that lead to null or low-expression alleles.
• To assess the prevalence of these expression variants in a tested population.

Main Methods:

• Development and application of a polymerase chain reaction using sequence-specific primers (PCR-SSP) system.
• The PCR-SSP system was designed to detect all previously sequenced HLA class I expression variants.
• The system also screens for mutations at nucleotide positions 621-627, a region prone to cytosine repeat variations.

Main Results:

• The developed PCR-SSP method successfully identified all previously characterized HLA class I expression variants.
• The study identified a significant mutation type involving insertions in a cytosine island (positions 621-627), leading to expression failure.
• HLA class I expression variants were detected in 0.53% (5 out of 931) of the tested samples.

Conclusions:

• A novel PCR-SSP method effectively detects HLA class I expression variants, including those caused by repeat mutations.
• The findings highlight the recurrence of cytosine repeat mutations as a cause of potentially null alleles across HLA-A, B, and C loci.
• This method enhances the accuracy of HLA typing, crucial for minimizing risks associated with allogeneic transplantation.