Molecular screening of the G3277A alteration in a Black South African diabetic population

Abstract

The diabetic disorder is a collection of genetic diseases with a common phenotype of impaired glucose homeostasis and affects many different organs, resulting in a clinically heterogeneous phenotype with strong genetic as well as environmental influences. The basis of diabetes is the aberrant production and utilisation of glucose, in conjunction with factors affecting the influence of insulin on the body and its role in glucose absorption. The mitochondrion has a vital role to play in energy production, and therefore warrants investigation. A mutation at position 3243 in the mitochondrial genome has been associated with the diabetic phenotype when expressed in heteroplasmic levels of approximately 30%. This mutation has been detected in the European diabetic population but is not detected in the Black South African diabetic population. In a previous study to determine the prevalence of the 3243 mitochondrial mutation in a Black South African diabetic cohort, another alteration, G3277A, was observed in ca. 3% of a small cohort investigated. In the present study it was investigated whether this alteration could be associated with the Black South African diabetic population. Blood samples collected from 222 diabetic and 237 non-diabetic individuals were analysed via RFLP and automated sequencing techniques for the presence of this G3277A alteration as well as the A3243G mutation in the samples that were sequenced. It was observed that seven control individuals and one patient individual harboured the G3277A alteration. None harboured the A3243G mutation but three novel alterations were detected. Via statistical analysis it was determined that the G3277A alteration was not in Hardy-Weinberg equilibrium in either the diabetic or non-diabetic populations, therefore no assumption regarding the association of these alterations with the type 2 diabetic phenotype could be made. It is therefore suggested that in the future larger groups of individuals are screened for the A3277G alteration.