Comparison of Q223R leptin receptor polymorphism to the leptin gene expression in Greek young volunteers Running title: Leptin polymorphism and leptin gene expression

Objective: The objective of the present study was to identify the leptin gene expression and the leptin receptor polymorphisms in blood samples and to correlate gene expression values with an-thropometric characteristics. Methods: Blood from 140 Greek young volunteers was subjected to pol-ymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP), for the genomic re-gion of Q223R polymorphism at codon 223 in the leptin receptor gene (LEPR) coding region. RNA extraction, cDNA synthesis and Quantitative Real-Time PCR was performed for assessing the expres-sion of the leptin gene (LEP). Results: Leptin gene was identified in all tested specimens and the gene was expressed in 88.9% of all volunteers with BMI < 25. In addition, it was observed that gene ex -pression is affected by various external factors, such as Body Mass Index (BMI), eating behavior, gender and age. It was also shown that as for the Q223R polymorphism (A to G) allele G occurs with a frequency of 100% in men with BMI > 30 and 75.9% in men and 88.9% in women with BMI 25-30.Volunteers with BMI 25-30 who were homozygous on the G allele were 50% and 77.8% in men and women respectively. All subjects with a BMI > 30 were homozygous on the G allele at 100%. Conclusions: In this small-scale study, results have shown that the leptin gene expression correlates with BMI and that the allele G in Q223R polymorphism is linked to overweight individuals.