Human platelet antigen allele frequencies in different Algerian populations

The frequencies of human platelet antigens (HPAs) vary between different populations and are a major determinant for the prevalence of HPA alloimmunization and its clinically associated entities. No report on HPA prevalence has previously been published for the Algerian populations which are ethnically diverse. The aim of this study was to determine the HPA allele frequencies in Algerian populations and to identify situations of incompatibility possibly leading to alloimmunization. A total of 485 healthy volunteer Algerian blood donors from different regions and representing different ethnic groups were included. HPA genotyping was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and/or polymerase chain reaction-sequence specific primer (PCR-SSP). The HPA-1 allele frequencies were close to the frequencies found in Caucasian populations. The presence of the molecule human leukocyte antigen (HLA)-DRB3*0101 (17.9%) increases the risk of alloimmunization. We observed an increase in the frequency of homozygous HPA-5b, particularly in the population of Annaba (7.61%) and the Mzab population (5.13%). The allele frequency HPA-2b (0.193-0.147) was similar to that seen in Sub-Saharan African populations. The high frequency of homozygotic HPA-2b (Kabyle 5%; Mzab 2.44% and Annaba 2.19%) could increase the risk of alloimmunization. GPIIb A(k) mutation (2614C>A) was found in these populations. This study is the first to report on HPA allele frequencies in Algerian populations. High allele frequencies were observed for HPA-1b (0.209-0.112), HPA-3b (0.411-0.312) and HPA-5b (0.217-0.087), leading to a high risk of alloimmunization in this population, especially the Mzab and the population of Annaba. Our results could have some impact in the diagnosis, prevention and treatment of alloimmune thrombocytopenia.