OBJECTIVETo study the contribution of genetic factors to the variance of serum leptin concentration in healthy, normotensive twins.

METHODSA total of 57 pairs of twins were investigated: 28 female and 19 male pairs of monozygotic(MZ) twins, and 6 female and 4 male pairs of dizygotic(DZ) twins. The zygosity of twins was determined by comparing the concordance of the genotype of nine fluorescence-labeled microsatellite markers. The genetic analysis was performed using the variance-based method. Serum leptin levels were determined in duplicate by a radioimmunoassay Kit (Linco Research, Inc., St. Charles, Missouri) as previously described.

RESULTSThe test of genetic variance revealed a significantly larger within-pair variance of serum leptin in the DZ twins, in comparison with the MZ twins. The corresponding heritability for serum leptin was 8%. Adjusted for BMI, gender, and uric acid (UA), the heritability for serum leptin was 0.18%. Log leptin correlated significantly with blood pressure (SBp r=0.355 P<0.001; DBp r=0.339 P<0.001). Stepwise multiple linear regression analysis revealed that only BMI, gender and UA were linked independently to serum leptin levels(R(2)=0.788, P<0.001).

CONCLUSIONThe above data indicate that environmental factors other than genetic factors are important determinants of leptinemia in normal subjects.

Adolescent ; Adult ; Body Mass Index ; Female ; Genotype ; Humans ; Leptin ; blood ; genetics ; Male ; Microsatellite Repeats ; genetics ; Middle Aged ; Twins, Dizygotic ; genetics ; Twins, Monozygotic ; genetics