The Distribution of Vitamin D Receptor Genotypes and Haplotypes in Southern Moroccan Population

It is well known that biological functions of the vitamin D receptor (VDR) may be affected by genetic variations in the VDR gene. The distribution of these variants either alone or combined in haplotypes, also show remarkable differences depending on the ethnicity of the population under study. Nevertheless, still little information about these variants are available from North African and Saharan populations. Here, we investigate the distribution of four common VDR gene polymorphisms (SNPs rs2228570, rs1544410, rs7975232 and rs731236) and their haplotypes in a southern Moroccan heterogeneous population constituted by individuals of Amazigh and Arab ancestry. In this study, were genotyped 260 individuals for four common SNPs in the VDR gene using restriction fragment length polymorphism analysis. Allelic and genotype frequencies were calculated, and relationships among the four VDR gene polymorphisms were assessed by measuring pair-wise linkage disequilibrium (LD). We then compared our results to those reported in several Mediterranean and International Hap Map Project populations. In the population of southern Moroccan area that we studied, the VDR rs2228570C-allele (71,5 %), rs1544410 G-allele (60,5 %), rs7975232 T-allele (60%) and rs731236 T-allele (66 %) all occur at unexpected high frequencies. Linkage disequilibrium (LD) analysis did not show any linkage between rs2228570 and the other investigated VDR SNPs. However, strong LD was found between SNPs (rs1544410- rs7975232- rs731236) located in the 3’ Untranslated Region (UTR), and that may explain the high frequencies of haplotypes GGT 36.5 % and ATC 27.2%. In spite of these results the distribution of VDR variants in the southern Morocco population was relatively not significant when compared to Mediterranean populations.