Associations of MC3R polymorphisms with physical activity in South African adolescents.
BACKGROUND
There is evidence demonstrating that the contribution of sedentary behavior and effect of physical activity on metabolic phenotypes is mediated by polymorphisms in genes.


METHODS
The type and frequency of physical activity was assessed by means of structured questionnaires in 1555 South African school learners. Anthropometric measurements, blood pressure, fasting blood glucose and lipids were measured using standard procedures. The effect of different types and frequency of physical activity on obesity-related traits was assessed in relation to MC3R T6K and V81I genotypes in 430 of the learners.


RESULTS
Levels of total cholesterol were significantly lower in learners carrying the MC3R T6K and V81I minor alleles, after adjusting for age, race, gender, and each specific physical activity category. An activity-by-genotype interaction was also detected: learners heterozygous for the V81I polymorphism and performed house chores often had reduced total cholesterol. Though no association was observed between frequency of physical activity and BMI, television viewing was significantly associated with an increase in height, weight and marginally with waist circumference.


CONCLUSIONS
Our findings suggest that physical activity even in the form of house chores has a positive effect on metabolic traits and this effect is further enhanced in the presence of MC3R polymorphisms.
Dept of Chemical Pathology, University of Stellenbosch, Cape Town, South Africa.
Yandiswa Y
YY
Yako
Mogamat S
MS
Hassan
Rajiv T
RT
Erasmus
Lize
L
van der Merwe
Susan
S
Janse van Rensburg
Tandi Edith
TE
Matsha
D000293:Adolescent; D001794:Blood Pressure / Q000235:genetics*; D002784:Cholesterol / Q000235:genetics*; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D005838:Genotype; D006801:Humans; D008055:Lipids / Q000235:genetics; D008297:Male; D009043:Motor Activity; D009765:Obesity / Q000235:genetics*; D010641:Phenotype; D011110:Polymorphism, Genetic; D044104:Receptor, Melanocortin, Type 3 / Q000235:genetics*; D057185:Sedentary Behavior; D013019:South Africa; D011795:Surveys and Questionnaires; D055105:Waist Circumference
D008055:Lipids; C505392:MC3R protein, human; D044104:Receptor, Melanocortin, Type 3; D002784:Cholesterol