Leptin levels and leptin receptor polymorphism frequency in healthy populations

Camille C Ragin,Michael Okobia,Emanuela Taioli,Francesmary Modugno,Jiangying Chen,Cher Dallal,Seymour Garte

doi:10.1186/1750-9378-4-s1-s13

Abstract

BackgroundThe leptin receptor gene (LEPR) polymorphism Q223R is one of the most common in the general population, and is thought to be associated with an impaired signaling capacity of the leptin receptor and with higher mean circulating levels of leptin. Leptin is a hormone primarily produced in adipose tissue. Increased levels of leptin have been positively correlated with obesity. We have determined the frequency of the leptin receptor polymorphism (LEPR Q223R) in healthy populations from various ethnic groups, and compared plasma leptin levels across the LEPR Q223R polymorphism in healthy African-Caribbean and Caucasian women.ResultsThe study population consists of 1,418 healthy subjects from various ethnic groups. The LEPR Q223R homozygous variant was observed overall in 19% of subjects (n = 1,418), with significant differences based on self reported ethnicity: the proportion of subjects with the homozygous variant was lower in Caucasians (14%, n = 883) than in African-Caribbean (n = 194), African-American (n = 36) and Asian/other ethnic groups (n = 26), (35%, 33% and 34.6% respectively); the frequency in Africans (20%), was similar to the overall study population. The mean ± standard deviation (SD), circulating leptin levels for African-Caribbean women was 44.7 ± 31.4 ng/ml, while for Caucasian women the mean was 42.4 ± 34.8 ng/ml. Adjusted circulating leptin levels in post-menopausal Caucasian women who were LEPR Q223R homozygous variant were marginally statistically significantly higher than in women with the wild-type genotype (p = 0.098). No significant differences in leptin levels by genotype were observed for African-Caribbean women, (heterozygous: p = 0.765, homozygous variant: p = 0.485).ConclusionThese findings suggest an association between mean circulating leptin levels and the LEPR Q223R genotype among post-menopausal Caucasian women.

Highlights

Leptin, a product of the ob gene, is a biologically active polypeptide (16 kDa) primarily produced in adipose tissue [1]
Some studies have reported that leptin stimulates the proliferation of normal and malignant breast epithelial cells [8] and others have suggested that leptin levels may be associated with breast cancer [9,10] as well as cancer at other sites [11]
For the overall study population, the frequency of the heterozygous (GA) and homozygous (AA) variants was 50% and 18.97% respectively and significant differences were observed based on ethnicity (p < 0.0001)

Summary

Introduction

A product of the ob gene, is a biologically active polypeptide (16 kDa) primarily produced in adipose tissue [1]. Leptin binds to the human leptin receptor, a cytokine receptor that promotes gene transcription via activating signal transduction pathways [12]. The LEPR polymorphism Q223R is one of the most common and is thought to be associated with an impaired signaling capacity of the leptin receptor; this polymorphism has been associated with higher mean circulating levels of leptin [15,16]. The leptin receptor gene (LEPR) polymorphism Q223R is one of the most common in the general population, and is thought to be associated with an impaired signaling capacity of the leptin receptor and with higher mean circulating levels of leptin. We have determined the frequency of the leptin receptor polymorphism (LEPR Q223R) in healthy populations from various ethnic groups, and compared plasma leptin levels across the LEPR Q223R polymorphism in healthy African-Caribbean and Caucasian women

Methods

Results

Conclusion