Mutation screening of the ENPP1 gene and its possible contribution to the development of obesity/overweight and metabolic syndrome in South African children

Abstract

Epidemiological reports have shown that South Africa, whilst a developing country, irs overweight and obesity prevalence rates in children is fast approaching those seen in the developed world. This country's population is unique in that it is made up of different ethnic groups with different socia-economic status, partly due to the past and present political environments in the country. South Africa, in particular, is faced with a rapid increasing childhood obesity of 10% among children under the age of two and 5-20% among those less than six years of age. The prevalence of obesity is increasing in children of all ages and represents the complex integration of genetic, behavioural and environmental influences. The Ectonucleotide Pyrophosphatase Phosphodiesterase 1 (ENPP1) gene is located on chromosome 6q22-q23; a locus linked to obesity and diabetes, spans 83 kb of genomic DNA and contains 25 exons. Studies in humans have shown a correlation between overexpression of ENPP1 and insulin resistance, obesity, and type 2 diabetes. ENPP1 has been implicated in up to 20% of Caucasian and 50% of Black communities suffering from obesity. The overall objective of the proposed study is to assess whether ENPP1 polymorphisms contribute to childhood obesity/overweight, and their association with components of metabolic syndrome in a South African Coloured population.

Subjects for this study were identified through a screening program that aimed to determine the prevalence of obesity in learners between the ages of 8 - 18 years from the Western Cape Province, South Africa. The first phase of the project was to clearly differentiate between obese subjects and controls. The cut-off points for obesity established by Cole and co-workers in 2000, and adopted by the International Obesity Task Force (IOTF), were used to classify the obese subjects.