Association between Haptoglobin Genotype Polymorphism and Type Two (2) Diabetes in Accra, Ghana

Abstract

Polymorphism of the haptoglobin (Hp) gene, characterized by alleles Hp1 and Hp2, gives rise to structurally and functionally distinct Hp protein phenotypes: Hp1-1, Hp2-1, and Hp2-2. The corresponding proteins have structural and functional differences that have influence on a particular disease. For example, Hp genotype is an independent risk factor for diabetic complications. In urban Ghana, type two diabetes mellitus (T2DM) affects at least 6% of adults. The aim of this study was to assess the association between Hp genotype polymorphism in T2DM patients in Accra. The study was a case control one. A total of 100 participants, 50 T2DM patients attending the Diabetes Clinic (Korle-Bu Teaching Hospital) and 50 healthy non-diabetic controls, were involved. Plasma glucose concentration was measured by the glucose-oxidase method. Fasting blood glucose was performed on all subjects except for the individuals with a history of T2DM. Hp genotype was determined by allele specific polymerase chain reaction (PCR). PCR produced Hp genotype-specific bands for the Hp1F, Hp1S, and Hp2 alleles. Statistical analyses revealed a significant difference in the Hp genotype distribution between diabetics and non-diabetics (χ 2 = 7.84, df = 2, p = 0.0198). Hp1-1 was the most frequent genotype among non-diabetics (58%) whilst Hp2-2 (38%) was most frequent genotype among diabetics. Majority of the diabetics were found in the Hp1S-1F and Hp2-2 genotype groups for diastolic BP (mmHg), systolic BP (mmHg) and FBG (mM). There was a strong association between DM and Hp2-2 genotype, followed by Hp2-1 (Hp1F-2 > Hp1S-2) with the least being Hp1-1 (Hp1F-1F, Hp1S-1F, Hp1S-1S). The risk of developing diabetes among people with Hp2-2 and Hp1F-2 genotypes was high. They can therefore be used as markers for an individual developing DM.