The A19G Polymorphism in the 5′ Untranslated Region of the Human Obese Gene Does Not Affect Leptin Levels in Severely Obese Patients

Abstract

Recently, the presence of different polymorphisms in the regulatory region of the ob gene has been associated with variations in leptin levels. However, the results of these studies are still contradictory. The aim of the present investigation was to evaluate the presence of the A19G polymorphism in an Italian population of obese patients and to verify its association with leptin levels and anthropometric, metabolic, and clinical parameters. Two hundred five obese patients [body mass index (BMI) > 36 kg/m2; 135 women and 70 men; mean age, 46.9+/-14.23 yr] were screened for presence of the polymorphism; 61 normal-weight controls (mean BMI, 21.05 kg/m2; 53 women, 8 men) were also screened to compare polymorphism frequency. For obese patients, BMI, waist-to-hip ratio, resting energy expenditure, body composition, fasting leptin, total cholesterol, high-density lipoproteins, triglycerides, and caloric intake were determined. Genotype frequencies in obese and control subjects were compared using the contingency table chi-square test; in obese subjects an ANOVA was performed to evaluate association between the polymorphism and several clinical parameters. No significant differences in genotype distribution between control and obese subjects were found. No significant correlations were found between this polymorphism and serum leptin levels and the other parameters considered. These findings confirm the results obtained in both a Finnish and a French population; taken together, these observations might rule out a significant role for the A19->G polymorphism in the regulation of leptin levels and other clinical, anthropometric, and metabolic parameters.

Non-Hodgkin's lymphoma, obesity and energy homeostasis polymorphisms

“…Using LEP 19GG as the referent group, the recalculated FL risk estimate for the LEP 19AA genotype is 0.6 (95% CI 0.3 -1.3), similar to the OR of 0.5 (95% CI 0.3 -0.8) presented here. As has been observed elsewhere, the BMIs of our controls were not correlated with LEP 19G4A (r ¼ 0.014, P ¼ 0.70) (Karvonen et al, 1998;Lucantoni et al, 2000), LEP À2548G4A (r ¼ À0.013, P ¼ 0.72) (Mammes et al, 1998;Le Stunff et al, 2000), LEPR 223Q4R (r ¼ À0.008, P ¼ 0.83) (Gotoda et al, 1997;Rosmond et al, 2000;Wauters et al, 2001) or APM1 276G4T (r ¼ À0.024, P ¼ 0.51) (Menzaghi et al, 2002;Fumeron et al, 2004). Moreover, this and the previous report by Skibola et al found little evidence that risks associated with BMI varied by genotype.…”

Polymorphisms in the leptin and leptin receptor genes in relation to resting metabolic rate and respiratory quotient in the Québec Family Study

“…The lower RQ might suggest that this genotype combination results in a more efficient leptin-leptin receptor signaling compared to the other genotypes. We found no associations between the 19A4G LEP variant and RMR or RQ, which is in agreement with findings in an Italian 48 and a Finnish 40 obese population. Obese individuals who carry the A19 allele showed significantly higher leptin concentrations compared to obese patients who were G19G homozygotes.…”

Mismatch Amplification Mutation Assay Real-Time PCR Analysis of the Leptin Gene G2548A and A19G Polymorphisms and Serum Leptin in Infancy: A Preliminary Investigation

“…As for G2548A, the frequency of the G allele observed in our sample was higher (0.67 vs. 0.41-0.60) than those reported for Tunisian [13] and especially for Turkish [12] and Iraqi [24] populations. Conversely, the frequencies for A19G were very similar to those reported for healthy patients worldwide, including Italy [25], other European countries [26,27], Tunisia [13] and the United States [15]. …”