Contribution of HLA class I (A, B, C) and HLA class II (DRB1, DQA1, DQB1) alleles and haplotypes in exploring ethnic origin of central Tunisians.

BACKGROUND: Estimation of HLA (Human leukocyte Antigen) alleles' frequencies in populations is essential to explore their ethnic origin. Anthropologic studies of central Tunisian population were rarely reported. Then, in this work, we aimed to explore the origin of central Tunisian population using HLA alleles and haplotypes frequencies. METHODS: HLA class I (A, B, C) and HLA class II (DRB1, DQA1, DQB1) loci genotyping of 272 healthy unrelated organ donors was performed by Polymerase Chain Reaction-Sequence Specific Oligonucleotide (PCR-SSO). We compared central Tunisians with other populations (Arabs, Berbers, Mediterraneans, Europeans, Africans, etc.) using alleles and haplotypes frequencies, genetic distances, Neighbour-Joining dendrogram and correspondence analysis. RESULTS: Among the 19 HLA A alleles, the 26 HLA B alleles, the 13 HLA C alleles, the 15 HLA DRB1 alleles, the 6 HLA DQA1 alleles and the 5 HLA DQB1 alleles identified in the studied population, HLA A*02 (22.8%), HLA B*50 (13.1%), HLA C*06 (21.8%), HLA DRB1*07 (17.8%), HLA DQA1*01 (32.1%) and HLA DQB1*03 (31.6%) were the most frequent alleles. The extended haplotypes HLA A*02-B*50-C*06-DRB1*07-DQA1*02-DQB1*02 (1.97%) was the most frequent HLA six-loci haplotype. CONCLUSION: Central Tunisians were very close to other Tunisian populations, to Iberians and North Africans. They were rather distant from sub-Saharan populations and eastern Mediterraneans especially Arabs although the strong cultural and religious impact of Arabs in this population.

Association between Human Leukocyte Antigen (HLA) DQB1*06 and HLA DQB1*03 and adverse outcomes in a group of critically ill patients with COVID-19 in Tunisia: a cross-sectional study.

Introduction: Human Leukocyte Antigen (HLA) system is a highly polymorphic genetic system associated with the prognosis of several infectious diseases. The aim of this study is to investigate the association of HLA polymorphism with the outcome of coronavirus disease 2019 (COVID-19) in Tunisian critically ill patients. Methods: this retrospective cross-sectional study included 42 consecutive patients hospitalized in intensive care unit (ICU) for COVID-19 in March 2021. Genotyping of HLA loci was performed by LABType™ sequence-specific oligonucleotide (SSO) typing kits (One lambda Inc, USA). Statistical analyses were performed using Statistical Package for Social Sciences (SPSS®) version 23.0. A p-value <0.05 was considered significant. Multivariable regression analysis was performed for the association between HLA polymorphism with adverse outcomes with adjustment for potential confounders such as age, sex, co-morbidities and blood type. Results: patients included in our study had a mean age of 64.5 ± 11.5 (34-83) years and were mainly men (64.3%; (n=27)). The most common cardiovascular risk factors were obesity (61.9%; (n=26)) and hypertension (26.2%; (n=11)). Thirty-two patients died (76.2%). Eleven patients (26.2%) required intubation during hospitalization. We found that HLA DQB1*06 allele was significantly associated with protection against mortality aOR: 0.066, 95% CI 0.005-0.821; p = 0.035. HLA DQB1*03 allele was significantly associated with protection against intubation aOR: 0.151, 95% CI 0.023-0.976; p = 0.047. Conclusion: it was found that there are 2 protective HLA alleles against COVID-19 severity and mortality in critically ill patients. This could allow focusing on people genetically predisposed to develop severe forms of COVID-19.