HLA-A, -B, -DR and -DQ allele and haplotype frequencies in the Moroccan population: a general population study

HLA class I and class II alleles and haplotypes of Algerian population from Algiers and neighbouring area

In this study, we aimed to investigate the current genetic diversity and provide additional insights into the origins of the Algerian population by analyzing the frequencies of HLA -A,-B,-DRB1,-DQB1 alleles and associated haplotypes. We analyzed 1,082 unrelated healthy Algerian individuals, who were potential kidney donors, recruited and assessed in the Immunology Department of CHU Mustapha in Algiers over a 10-year period (2009-2019). HLA genotyping was performed by Polymerase Chain Reaction Sequence Specific Primers (PCR-SSP). The allelic typing estimate and haplotype frequencies were calculated using the R studio® software and Haplotype frequency estimation from the website https://hla-net.eu/. We identified a total of 20 HLA-A alleles, 31 HLA-B alleles, 13 HLA-DRB1 alleles and5 HLA-DQB1 alleles. Regarding the allele frequency, the haplotype frequency and the distribution with other population database, we were able to provide a description of Algerian genetic background and draw some anthropogenetic conclusions. This study of HLA polymorphism in the Algerian population shows a strong genetic similarity with the populations of southern Europe and North Africa (Morocco, Tunisia and Libya) with which it has shared a common history since antiquity. In addition to its contribution to anthropogenetics, our study, serve as a reference database for studies exploring associations between the HLA system and certain pathologies.

Distribution of Major HLA-A, -B, -DR, and -DQ Loci Potentially Associated with Multiple Sclerosis in a Healthy Population from Southern Morocco

Background: Many factors contribute to the development and the progression of Multiple Sclerosis (MS), including Human Leukocyte Antigen (HLA) molecules. Some of them are considered as predisposing, like DRB1*15, DRB1*13, DRB1*03, DRB1*04, DQB1*06, DQB1*02, while HLA A2, HLA B44, DRB1*11, and DRB1*12 are rather considered as protective. Data about such associations in the Moroccan population remain unknown. The aim of this study was to determine the frequency of HLA class I (A and B) and II (DR and DQ) linked to Multiple Sclerosis (MS) in a healthy population from the South of Morocco. Materials and Methods: A cross-sectional study was carried out over the 2016-2023 period on 685 Moroccan healthy individuals, including 355 males and 330 females. Of the total sample tested, 685 underwent HLA class I typing, of which 305 also benefited from HLA class II typing. HLA class I typing was executed using the CDC (complement dependent cytotoxicity) technique (OneLambda™, Los Angeles CA, USA), and HLA class II typing was performed by either PCR-SSP (sequence-specific primer, OneLambda) or PCR-SSO (sequence-specific oligonucleotides) using the Luminex Xmap (Lifecodes, Immucor, Peachtree, Corners, GA, USA) system. Results: From different HLA molecules potentially predisposing to MS, our investigations showed that DRB1*03, DRB1*13, DRB1*15, DRB1*04, and DQB1*02 were observed in 19.2%, 15.8%, 13.31%, 12.7% and 31% respectively, while the frequency of those considered as protective, namely HLA-A2, HLA-B44, and HLA-DRB1*11 was 23.31%, 9.21% and 10.1% respectively. Conclusions: The findings of our study give evidence that among predisposing HLA class II molecules, DR allele groups were more prevalent, mostly DRB1*03, with also a high frequency of DQB1*06, while HLA-A2 marked the supposed protective specificities. These results need to be supported by complementary studies particularly in MS patients.

The genetic heterogeneity of Arab populations as inferred from HLA genes

This is the first genetic anthropology study on Arabs in MENA (Middle East and North Africa) region. The present meta-analysis included 100 populations from 36 Arab and non-Arab communities, comprising 16,006 individuals, and evaluates the genetic profile of Arabs using HLA class I (A, B) and class II (DRB1, DQB1) genes. A total of 56 Arab populations comprising 10,283 individuals were selected from several databases, and were compared with 44 Mediterranean, Asian, and sub-Saharan populations. The most frequent alleles in Arabs are A*01, A*02, B*35, B*51, DRB1*03:01, DRB1*07:01, DQB1*02:01, and DQB1*03:01, while DRB1*03:01-DQB1*02:01 and DRB1*07:01-DQB1*02:02 are the most frequent class II haplotypes. Dendrograms, correspondence analyses, genetic distances, and haplotype analysis indicate that Arabs could be stratified into four groups. The first consists of North Africans (Algerians, Tunisians, Moroccans, and Libyans), and the first Arabian Peninsula cluster (Saudis, Kuwaitis, and Yemenis), who appear to be related to Western Mediterraneans, including Iberians; this might be explained for a massive migration into these areas when Sahara underwent a relatively rapid desiccation, starting about 10,000 years BC. The second includes Levantine Arabs (Palestinians, Jordanians, Lebanese, and Syrians), along with Iraqi and Egyptians, who are related to Eastern Mediterraneans. The third comprises Sudanese and Comorians, who tend to cluster with Sub-Saharans. The fourth comprises the second Arabian Peninsula cluster, made up of Omanis, Emiratis, and Bahrainis. It is noteworthy that the two large minorities (Berbers and Kurds) are indigenous (autochthonous), and are not genetically different from "host" and neighboring populations. In conclusion, this study confirmed high genetic heterogeneity among present-day Arabs, and especially those of the Arabian Peninsula.

HLA class I (-A, -B, -C) and class II (-DR, -DQ) polymorphism in the Mauritanian population

BACKGROUND

HLA antigens have been widely studied for their role in transplantation biology, human diseases and population diversity. The aim of this study was to provide the first profile of HLA class I and class II alleles in the Mauritanian population.

METHODS

HLA typing was carried in 93 healthy Mauritanian blood donors, using single specific primer amplification (PCR-SSP).

RESULTS

Occurrences of the main HLA class I (-A, -B, -C) and class II (-DR, -DQ) antigens in the general population showed that out of the 17 HLA-A allele groups detected, five main HLA-A allele groups: A*02 (18.42%), A*01 (14.04%), A*23 (14.04%), A*30 (13.16%) and A*29 (12.28%) were the most common identified along other 12 relatively minor allele groups. Twenty three allele groups were observed in the locus B of which B*07 (13.46%) was the most prevalent followed by B*15, B*35, B*08 and B*27 all, with a frequency between 7 to 8%. Three prevalent HLA-C allele groups (C*02: 35.09%, C*07: 20.19% and C*06: 13.6%) were detected. The main HLA class II observed allele groups were: DRB1*13 (27.42%), DRB1*03 (24.73%), DRB1*11 (13.98%), DQB1*03 (36.03%), DQB1*02 (22.06%) and DQB1*05 (18.8%). Except for few haplotype in class I (A*02-B*07: 4.45%, A*02-C02: 10%, A*23-C*02: 8.8%, B*07-C*02: 8.8%, B*15-C*02: 8.8%) and in class II (DRB1*13-DQB1*06: 11.94%, DRB1*03-DQB1*02:11.19% and DRB1*03-DQB1*03: 10.45%), the majority of locus combination were in the range of 2-3%. A single predominant haplotype C*02-DRB1*03 (16.67%) was found.

CONCLUSIONS

These results, in agreement with previous data using different tissues markers, underlined the ethnic heterogeneity of the Mauritanian population.

[The HLA system in the Moroccan population: General review]

The Moroccan population is an interesting study model of Human Leukocyte Antigen (HLA) polymorphism given its ethnic and genetic diversity. Through an analysis of the literature, this work proposes to establish a balance of knowledge for this population in the field of histocompatibility: HLA diversity, anthropology, transplantation and HLA associations and diseases. This analysis shows that the HLA system has not been fully explored within the Moroccan population. However, the results obtained allowed us to initiate a database reflecting the specific healthy Moroccan population HLA polymorphism to identify immigration flows and relationships with different people of the world and to reveal the association of certain HLA alleles with frequent pathologies. We also propose to analyze the reasons hindering the development of this activity in Morocco and we will try to identify some perspectives.

Polymorphisms of HLA-A, -B, -Cw and DRB1 antigens in Moroccan patients with ankylosing spondylitis and a comparison of clinical features with frequencies of HLA-B*27

Ankylosing spondylitis (AS) is very often associated with human leukocyte antigen (HLA), particularly HLA-B*27. However, the strength of this association and clinical features may vary in different ethnic groups. Our study aims to assess the distribution of HLA-A, -B, -Cw and DRB1 alleles in Moroccan patients with AS and to compare the clinical features of AS and the frequencies of HLA-B27 in patients from Morocco with other series. Seventy-five patients diagnosed with AS and assessed for clinical manifestations were selected and compared to 100 healthy controls. HLA class I and II antigens were typed by polymerase chain reaction sequence-specific oligonucleotide. HLA-B27 subtypes were studied by polymerase chain reaction amplification with sequence-specific primers. HLA-B27 was found in 64% of patients. It was positively associated with younger age at disease onset, family history, and uveitis while it had a negative association with late onset. Six B*27 subtypes were identified in the AS group. HLA-B*2705 and B*2702 were the most common observed subtypes. Among other HLA genes, a significant increase in the prevalence of HLA-Cw*02 and HLA-DRB*15 was found in AS patients. HLA-B27 is involved in the predisposition of AS in the Moroccan population. HLA-B*2705 and B*2702 were the predominant subtypes supporting previous reports in Caucasian spondyloarthropathies. Other HLA genes, HLA-Cw*02 and HLA-DRB1*15, seem to confer predisposing effect to the disease. However, the lower frequency of HLA-B27 compared to the literature in our study suggests the existence of different genetic and/or environmental factors in Morocco.

Moroccan study of HLA (-A, -B, -C, -DR, -DQ) polymorphism in 647 unrelated controls: Updating data

The scope of this study is to investigate the HLA (Human Leukocyte Antigen) distribution and polymorphism in a large sample of healthy Moroccans in order to extend and update the available data. 647 unrelated Moroccan controls originating from diverse regions of the country were typed using microlymphocytotoxicity for HLA-A and -B, sequence-specific-primer amplification for -C, -DR, and -DQ and Luminex HD for specific -DR. The most frequent allele groups detected were HLA-A2 (19.2%), -B44 (12.4%), -C*07 (24.4%), -DRB1*03 (16.9%), -DRB1*04 (18.4%), -DQB1*02 (28.7%) and -DQB1*03 (27.8%). The most predominant specific alleles found for DRB1 were: *03:01, *04:02, *04:05, *07:01, *11:01, *13:02 and *15:01. Rare allelic variants were detected, for the first time in Moroccan population, at the DRB1*03 (*03:52, *03:54, *03:56), DRB1*07 (*07:07, *07:11, *07:16) and DRB1*11 (*11:70) locus. The most frequent haplotypes were: A2-B44, A30-B18, A2-C*16, A30-C*06, B14-C*08, B58-C*07, B45-C*06, DRB1*03-DQB1*02, DRB1*04-DQB1*03, DRB1*07-DQB1*02 and DRB1*15-DQB1*06. Comparison of genetic distances and haplotypes with other populations shows that the Moroccans are genetically closer to North Africans and Europeans than to sub-Saharan Africans. Our results reflect the high degree of HLA polymorphism in the Moroccan population and provide a useful baseline of healthy Moroccan controls for disease association and anthropological studies.

Analysis of HLA-A, -B, -C, -DR, -DQ polymorphisms in the South Tunisian population and a comparison with other populations

BACKGROUND

The Human Leucocyte Antigen (HLA) system is often used as a genetic marker for analysing populations. HLA antigen distribution among the Tunisian population is not well defined because of the lack of a general population study.

AIM

The aim of the present study was to investigate the polymorphism of HLA-A, -B, -C, -DR and -DQ loci in the South Tunisian population.

SUBJECTS AND METHODS

This study has investigated HLA-A, -B, -C, -DR and -DQ polymorphisms in 123 unrelated healthy individuals originating from the south of Tunisia. HLA class I was studied by serology and completed by polymerase chain reaction-sequence specific primer (PCR-SSP). HLA class II was performed using PCR-SSP.

RESULTS

The most common alleles were A-2 (0.2154), B-44 (0.1179), C7 (0.2114), DR4 (0.1626) and DQ2 (0.313). A1-B-8-C7-DR3-DQ2 (2.84%) was the predominant haplotype in this population. Comparisons with data of other worldwide populations based on phylogenetic tree and multidimensional scaling analysis were done. This study suggests that both HLA class I and class II polymorphism specificities demonstrate a high diversity in this South Tunisian population, which reflects ancient and recent admixture with neighbouring populations.

CONCLUSION

The results provide useful information for further studies of Tunisian population evolution, anthropology and for resolving HLA frequencies when searching for HLA-compatible donors in transplantation and for the analysis of disease associations.

HLA-A, -B and -DRB1 allele frequencies in Cyrenaica population (Libya) and genetic relationships with other populations

The frequencies of HLA-A, HLA-B and HLA-DRB1 alleles in 118 unrelated Libyans from Benghazi (Cyrenaica) were analysed using high resolution typing and compared with other populations. Their relatedness has been tested by correspondence analyses and principal component analysis. The most frequent HLA-A alleles were A(∗)02:01:01:01 (15.7%), A(∗)01:01:01:01 (11.4%) and A(∗)03:01:01:01 (9.3%). For the HLA-B locus, the commonest allele was HLA-B(∗)50:01:01 (14.4%) followed by B(∗)51:01:01 (9.8%) and B(∗)08:01:01 (6.4%). For the HLA-DRB1 locus, the commonest was HLA-DRB1(∗)07:01:01:01 (16.9%) followed by DRB1(∗)03:01:01:01 (13.6%) and DRB1(∗)13:02:01 (9.3%). The most frequent two-locus haplotypes were HLA-A(∗)02:01:01:01-B(∗)07:02:01 (3.0%) and HLA-B(∗)50:01:01-DRB1(∗)07:01:01:01 (9.6%), and three-locus haplotypes were HLA-A(∗)02:01:01:01-B(∗)50:01:01-DRB1(∗)07:01:01:01 (4.2%) and HLA-A(∗)11:01:01-B(∗)52:01:01:01-DRB1(∗)15:02:01 (2.5%). This study is the first on the HLA status of a Libyan population. The results, when compared to similar HLA data obtained previously from African and Mediterranean populations, indicate genetic influences from several ethnic groups. Moreover, the differences in the HLA allele frequencies between the Libyan population and others reveals that significant admixture has occurred between the original Berber inhabitants and neighbouring and more distant populations, even though a strong genetic Berber substratum remains. These data will be of value to future anthropological and disease association studies involving the Libyan population.

HLA-B27 Prevalence in Arab Populations and Among Patients with Ankylosing Spondylitis: Table 1

Objective.

To investigate prevalence of HLA-B27 among general Arab populations and among patients with ankylosing spondylitis (AS), and to review published data.

Methods.

The prevalence of HLA-B27 was studied among 2579 unrelated healthy Jordanians, almost equally divided among Palestinian refugees and natives of Jordan, reflecting the general population of Jordan. The prevalence of HLA-B27 was also studied among 129 patients with AS, 70 from Jordan, and the remaining 59 from Qatar. HLA typing was performed by standard 2-stage micro-lymphocytotoxicity method. We also reviewed published English language studies of HLA-B27 in Arab patients with AS and general populations retrieved through Medline and cross-reference search.

Results.

We observed that the general prevalence of HLA-B27 among Jordanians is 2.4%; while the reported prevalence ranges between 2% and 5% among major Arab populations. The prevalence of HLA-B27 among patients with AS is 71% in Jordan and 73% in Qatar, while the reported prevalence from pooled published data from various Arab populations is 64%.

Conclusion.

From these data one can conclude that HLA-B27 is present in about 2% to 5% among major Arab populations and that its prevalence in Arab patients with AS is closer to 70%.

Distribution of HLA class I and II genes in ankylosing spondylitis patients from Morocco

OBJECTIVES

In Morocco, the patients affected by ankylosing spondylitis (AS) presents a high frequency of coxitis. Our study reports, for the first time, the polymorphism of Human Leukocyte Antigen (HLA) class I and class II molecules in the Moroccan patients.

METHODS

Forty-six patients diagnosed with an AS and coxitis were compared to a group of 183 healthy controls matched by age, sex and ethnic origin. The HLA typing was performed using microlymphocytotoxicity for the class I (-A, -B) and PCR-SSP for the class II (-DR, -DQ).

RESULTS

We found a significant increase of the HLA-B27 antigen frequency (P<0.0001, RR=20.9) in AS patients (29.3%) compared to the controls (3.2%) and a significant decrease in the frequency of HLA-B12 and HLA-B18 antigens. Examination of HLA class II distribution shows a significant increase of the HLA-DRB1*11 allele frequency in patients (P<0.0001). Concerning HLA-DQB1* alleles, no significant difference between patients and controls was appreciable.

CONCLUSIONS

The HLA-B27 antigen is involved in the predisposition to the AS with coxitis in the Moroccan population. However, the low frequency observed in our population suggests the existence of other genetic and/or environmental factors. Other HLA genes seem to confer a predisposing effect (DRB*11) or a protective effect (B12 and B18) against the disease.

Correlation between genetic HLA class I and II polymorphisms and anthropological aspects in the Chaouya population from Morocco (Arabic speaking)

The aim of this study was to provide genetic and anthropological information on the Chaouya (CH), an Arabic-speaking population living in West Morocco, Atlantic coast (Settat). In 98 unrelated healthy CH volunteers, we first investigated the human leukocyte antigen (HLA) class I and II allele polymorphisms using a sequence-based typing method and examined haplotypes and relatedness of this group to other African and Mediterranean populations. The study showed the close relatedness with Tunisian population and other North Africans, together with a strong influence of various immigrations, mainly Spaniards, French, and Portuguese, as expected. Nevertheless, analysis of class II allele frequencies (afs) showed that Oromo and Amhara Ethiopian groups cluster together with the Berbers and other North Africans, confirming the relationship between these populations (Afro-Asiatic linguistic group, Hamites). South and sub-Saharan Africans cluster separately at a great distance from CH, except the sub-Saharan Bantu population from Congo Kinshasa, which shows a relatively close genetic relationship ascribable to the effect of a diversifying selection. On the other hand, considering HLA class I afs analyses, it was noteworthy that CH grouped together with sub-Saharans, showing a close genetic distance mainly with Ugandas and Kenians Luo.