[1] NW Univ, Ctr Genome Res, ZA-0020 Pretoria, South Africa
[2] DNAbiotec Pty Ltd, ZA-0020 Pretoria, South Africa
[3] Tech Univ Dresden, Med Fac Carl Gustav Carus, Dept Endocrinopathies & Metab Dis, D-01307 Dresden, Germany
[4] NW Univ, Sch Physiol Nutr & Consumer Sci, ZA-2520 Potchefstroom, South Africa
[5] Univ Pretoria, Dept Clin Epidemiol, ZA-0001 Pretoria, South Africa