Limitations of human leukocyte antigen molecular typing methods for patients with main disease relapse after hematopoietic stem cell transplantation

Aim. The work purposed to compare molecular typing methods with different resolutions in clinical cases without loss of heterozygosity (LOH) in HLA genes. Methods. HLA typing was performed using molecular techniques based on sequence-specific primers (SSP) or high-resolution sequencing (NGS and Sanger sequencing). Results. the presence of an extra allelic variant in testing DNA samples was determined only with the low-resolution SSP method. At the same time, any type of sequencing did not allow for distinguishing donors' alleles from patients. Conclusion. Despite the high sensitivity of NGS and Sanger sequencing, the use of these methods is associated with difficulties in accurately determining the absence of HLA-LOH.