Leptin receptor LYS109ARG, GLN223ARG, SER343SER polymorphisms and obesity: Linkage disequilibrium and haplotype block analysis in Jeddah city.

Single nucleotide polymorphisms in leptin receptor gene, which interacts with leptin hormone (LEP(may play an important role in the pathophysiology of human obesity. The current study aimed to investigate whether LEPR polymorphismswere associated with incidence of obesity or no in Saudi study group. A case –control study was conducted with 109 subjects from Jeddah, Saudi Arabia. Genomic DNAs were used as templates in polymerase chain reaction (PCR) with pairs of primers designed to amplify exons 4, 6 and 9 of the human leptin receptor gene. Genotype and allele frequencies were determined by PCR reaction followed by restriction fragment length polymorphism techniques.A highly significant association between Lys109Arg, and Ser343Ser polymorphisms and incidence of obesity was observed (P= 0.017). Whereas no significant association between (Lys109Arg, Gln223Arg) and (Gln223Arg, Ser343Ser) combinations and incidence of obesitywas detected (P= 0.38, 0.195 respectively). There was a preference for genotypes TT/TC and allele T of Ser343Ser SNP in obese subjects. It seems that the effect of polymeric sites Lys109Arg, Gln223Arg on incidence of obesity was abolished when the three SNPs was combined. The only key player on incidence of obesity was Ser343Ser polymorphism. In conclusion, the data achieved pointed to the genetic predisposition of LEPR variants in Saudi population. The impact of Ser343Ser polymorphism on incidence of obesity may varies among populations as a result of distinct differences in their allele distributions.