The prevalence of maturity onset diabetes of the young (Mody) in a population from the Western Cape

Abstract

Background: Maturity Onset Diabetes of the Young (MODY) is a monogenic type of diabetes caused by a single gene mutation. Up to date 14 different MODY subtypes have been identified. Mutations in the glucokinase (MODY 3) and hepatic nuclear factor 1 alpha (HNF1A) (MODY 2) are the most frequent causes of MODY in all populations studied. Patients with MODY are misdiagnosed with type 1 or type 2 diabetes. Identifying patients with MODY is important as it affects treatment, for example, MODY 2 patients need no treatment, whereas those diagnosed with MODY 3 are very sensitive to low doses of sulphonylureas. To date, no data is available on the prevalence of MODY in populations from Africa. Thus, we aimed to investigate and report on the incidence of MODY, specifically mutations in the HNF1A gene in a population from the Western Cape. Methods: In this study, we screened for HNF1A MODY (MODY 3) mutations (rs115080759, rs140491072 rs137853245, and rs142318174) in 1639 (males = 406) individuals using real-time PCR. Positive MODY samples were confirmed by subsequent sequencing. All individuals underwent an oral glucose tolerance test. Results: The mean age of participants was 47.1±15.6 in males and 49.9±15.1 females. We identified 12 (0.73%) individuals with HNF1A gene polymorphisms; 12/1642 of rs115080759. Seven participants with a SNP in rs115080759 presented with normoglycemia, one with prediabetes, and four with diabetes. No polymorphism was detected in three SNPs; rs140491072, rs137853245 and rs142318174. Discussion and conclusion: To our knowledge, this is the first African study on MODY, and the incidence is similar to that reported in other studies. The results suggest that MODY is misdiagnosed with other types of diabetes in Africa; therefore, our findings support the introduction of diagnostic genetic testing for MODY in South Africa.