Heritability of leptin levels and the shared genetic effects on body mass index and leptin in adult Finnish twins.
OBJECTIVE
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.


METHODS
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.


METHODS
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.


CONCLUSIONS
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
University of Helsinki, Department of Public Health, The Finnish Twin Cohort Study, Helsinki, Finland. Jaakko.Kaprio@Helsinki.Fi
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Kaprio
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Eriksson
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Lehtovirta
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Koskenvuo
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Tuomilehto
D000368:Aged; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight / Q000235:genetics*; D015331:Cohort Studies; D004777:Environment; D005260:Female; D005387:Finland; D006801:Humans; D020738:Leptin / Q000097:blood* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D009765:Obesity / Q000097:blood / Q000235:genetics*; D012727:Sex Characteristics; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*
D020738:Leptin