January 2001, Volume 25, Issue 1, Pages 132 - 137

Paper

Heritability of leptin levels and the shared genetic effects on body mass index and leptin in adult Finnish twins J Kaprio1,5, J Eriksson2, M Lehtovirta3, M Koskenvuo4 & J Tuomilehto2 1University of Helsinki, Department of Public Health, The Finnish Twin Cohort Study, Helsinki, Finland     2National Public Health Institute, Helsinki, Finland     3Helsinki University Central Hospital, Department of Internal Medicine, Helsinki, Finland     4University of Turku, Department of Public Health, Turku, Finland     5Department of Public Health and General Practice, University of Oulu, Oulu, Finland     Correspondence to: J Kaprio, The Finnish Twin Cohort Study, Department of Public Health, University of Helsinki, P.O. Box 41, Mannerheimintie 172, SF-00014 Helsinki, Finland. E-mail: Jaakko.Kaprio@Helsinki.Fi

Keywords

body mass index;   leptin;   twins;   genetic models

Abstract

OBJECTIVES: Leptin is involved in the regulation of body weight, but the relative role of genetic and environmental influences on inter-individual variation in leptin levels is unknown. DESIGN AND SUBJECTS: To investigate the genetic and environmental contributions to the association of body mass index (BMI) with serum leptin levels, 58 monozygotic (MZ, 27M, 31F), and 74 like-sexed dizygotic (DZ, 32M, 42F) Finnish twin pairs aged 50-76 y were studied. MEASUREMENTS: Serum leptin levels, weight, height, hip and waist measurements. RESULTS: Women had higher mean leptin levels (16.8±9.5 ng/ml), and more overall variability in leptin levels than men (6.4±3.5 ng/ml; P<0.0001). Leptin levels correlated highly with BMI in men and women. Among women, the MZ and DZ pairwise correlations for leptin were 0.41 (P=0.009) and 0.07 (P=0.32), respectively. Among men the MZ and DZ pairwise correlations for leptin were 0.47 (P=0.006) and 0.23 (P=0.10). Univariate twin analysis indicated that, among women, 34% and, among men, 45% of the variance in leptin can be attributed to additive genetic effects, and the remainder to unique environmental effects. Significant non-additive genetic or shared familial effects could not be demonstrated. A bivariate twin analysis of leptin and BMI indicated that the correlation between additive genetic effects on leptin and BMI was 0.79 (95% CI 0.68-0.86) in women, and 0.68 (0.51-0.80) in men. The correlation between environmental effects on leptin and BMI was 0.77 (95% CI 0.66-0.85) in women, and 0.48 (0.26-0.66) in men. CONCLUSION: Leptin levels are moderately heritable in older adults, and a substantial proportion of genetic effects are in common on leptin levels and obesity in both women and men. International Journal of Obesity (2001) 25, 132-137

Received 20 March 2000; Revised 4 August 2000; Accepted 7 September 2000

^© Macmillan Publishers Ltd 2001