Determination of the CCR5∆32 frequency in Emiratis and Tunisians and the screening of the CCR5 gene for novel alleles in Emiratis.
BACKGROUND
The chemokine receptor components play crucial roles in the immune system and some of them serve as co-receptors for the HIV virus. Several studies have documented that variants in chemokine receptors are correlated with susceptibility and resistance to infection with HIV virus. For example, mutations in the chemokine receptor 5 gene (CCR5) resulting in loss-of-function (such as the homozygous CCR5∆32) confer high degree of resistance to HIV infection. Heterozygotes for these variants exhibit slow progression to AIDS. The prevalence of CCR5 polymorphisms varies among ethnic and geographical groups. For example, the CCR5∆32 variant is present in 10-15% of north Europeans but is rarely encountered among Africans. This study aims to identify the prevalence of some CCR5 variants in two geographically distant Arab populations (namely Emiratis and Tunisians).


METHODOLOGY
The prevalence of CCR5 gene variants including CCR5∆32, FS299, C101X, A29S and C178R has been determined using PCR and direct DNA sequencing. A total of 403 unrelated healthy individuals (253 Emiratis and 150 Tunisians) were genotyped for the CCR5∆32 variant using PCR amplification and gel electrophoresis. In addition, 200 Emiratis have been screened for other SNPs using Sanger DNA sequencing.


RESULTS
Among Emiratis, the allele frequency of the CCR5∆32 variant has been found to be 0.002. In addition, two variants L55Q and A159 were found at a frequency of 0.002. Moreover, the prevalence of the CCR5∆32 variant in Tunisians was estimated to be 0.013 which is relatively higher than its frequency in Emiratis but lower than Europeans.


CONCLUSION
We conclude that the allele frequency of the most critical CCR5 polymorphism (∆32) is extremely low among Emiratis compared to other Arabs and North Europeans. In addition, very low allele frequencies of other CCR5 polymorphisms have been detected among Emiratis.
['Al-Jaberi|Sara A|SA|', 'Ben-Salem|Salma|S|', 'Messedi|Meriam|M|', 'Ayadi|Fatma|F|', 'Al-Gazali|Lihadh|L|', 'Ali|Bassam R|BR|']
D000163:Acquired Immunodeficiency Syndrome D000483:Alleles D005006:Ethnicity D017353:Gene Deletion D005787:Gene Frequency D020022:Genetic Predisposition to Disease D006579:Heterozygote D006720:Homozygote D006801:Humans D016133:Polymerase Chain Reaction D011110:Polymorphism, Genetic D044469:Racial Groups D019713:Receptors, CCR5 D014416:Tunisia D014479:United Arab Emirates
CCR5∆32 Emiratis Chemokine receptors CCR5 polymorphisms Arab populations PCR DNA A Adenine CC-chemokine receptor 5 CCR or CXCR Delta32 variant Desoxyribonucleic acid G Guanine Polymerase chain reaction T Thymine UAE United Arab Emirates