The serum leptin level and body mass index in Melanesian and Micronesian Solomon Islanders: Focus on genetic factors and urbanization

Objectives: This study examined the association between the serum leptin level and body mass index (BMI) and the effects of urbanization and polymorphisms of leptin ( LEP ) or leptin receptor ( LEPR ) genes on the leptin level in three Solomon Islands populations. Methods: A Melanesian population living in a remote area (participants: 106 males and 106 females, ages: 18–74 years), a Melanesian population in an urban area (89 and 94, 18–79 years), and a Micronesian population who migrated to a peri‐urban area in the 1960s (84 and 69, 18–71 years) were studied. Anthropometric and serum leptin measurements and genotyping for LEP G‐2548A and LEPR K109R and Q223R were performed. Results: The prevalence of obesity (BMI ≥ 30 kg/m 2 ) was the highest in the Micronesian population (30.1%), followed by the urban (18.6%) and the rural (2.4%) Melanesian population. The serum leptin concentration was the highest in the urban Melanesian, followed by the Micronesian and the rural Melanesian populations ( P < 0.05). Interestingly, the parameter coefficients of the leptin concentrations on the BMIs were nearly identical in the urban and rural Melanesians after adjusting for age and gender. The LEPR 223Q/Q genotype was associated with an increased leptin level only in the Micronesian population after adjusting for BMI ( P = 0.0008 and 0.0016 referenced to the Q/R and the R/R types, respectively). Conclusions: These observations suggest that the increase in obesity in the Micronesians had a genetic component while that in Melanesians might have been related with the urbanization. Am. J. Hum. Biol., 2011. © 2010 Wiley‐Liss, Inc.