Identification of Human Leukocyte Antigen (HLA) Patterns in Beta-Thalassemia Patients and their Relevance to the Mutational Spectrum of the Human Beta-Globin Gene (HBB)

Abstract

Aims: HLA genotyping is beneficial in both clinical and research settings in order to understand the mechanism of associated diseases as well as organ transplantation. Beta-Thalassemia is endemic in Saudi Arabia. Studies showed more than 200 mutations affecting the HBB gene thus causing the disease with the IVS-1-5 mutation is considered the most common mutation in KSA. HLA matching in beta-thalassemia patients can support therapeutic interventions through hematopoietic stem cell transplantation (HSCT) as It is estimated that only 30% of patients can find an HLA-identical donor within their families. Methods: We have investigated the genetic polymorphism of 16 Short Tandem Repeat (STR) loci (D6S291, TAP1, D6S2880, D6S1014, D6S2973, MICA, MOGc, MIB, MIB outer, D6S2674, D6S2959, D6S2908, Ring3CA, D6S2812, D6S248 and D6S2707) in 15 transfusion-dependent beta thalassemia patients’ and 15 healthy volunteers using a fluorescent-labelled singleplex-PCR typing method. Results: The result showed wide variation in alleles and high level of genetic polymorphisms. In addition, we found a high level of homozygosity in patients samples at 3 STR loci; Ring3CA, D6S2812 and D6S248 where this homozygosity is significantly associated with the IVS-I-5 mutation (p-value less then 0.05, less then 0.001 and less then 0.001 respectively). Conclusion: We conclude that HLA matching using the fluorescent-labelled singleplex-PCR typing method provides a useful technique supporting HSCT as well as raising questions about the potential association between homozygosity at certain STR markers and particular HBB mutations.