H3Africa PI: David Kateete
Institution: Makerere University
Project Affiliation: BRecA
Background: Studies show that the DBP gene located at 4q12-q13 is highly polymorphic with over 120 variants (Bikle & Schwartz, 2019). These genetic variants affect the distribution of vitamin D in the circulatory system, leading to vitamin D deficiency and compromised immunity (Alhomsi et al., 2020). The two extensively studied non-synonymous DBP single nucleotide polymorphisms (SNPs) rs7041 and rs4588 occur in different populations (Santos et al., 2017). The wild-type Gc1F genotype is predominantly found in the African population, with a low frequency of Gc2 and Gc1S genotypes, and it is associated with low vitamin D levels in whites. According to previous research minor alleles exhibit tendencies of being risk alleles of disease. The aim of this study was to explore the DBP gene polymorphism and the risk of disease among TB patients and household contacts with and without HIV infection.
Methods: This was across-sectional study with 53 active tuberculosis patients attending Kiruddu Referral Hospital, 23 latent tuberculosis individuals, and 27 individuals without tuberculosis infection from the KTB cohort. These were aged between 12 to 65 years. DNA extraction and PCR were performed and a product of 498 bp was obtained. We genotyped the DBP gene by Sanger sequencing and the single nucleotide polymorphisms were identified using the BioEdit tool.
Results: The study frequency distributions of the DBP genotypes were reported as 97% Gc1F, 2% Gc2 and 1% Gc1S and Hardy-Weinberg equilibrium analysis was in equilibrium, D’= 0. Majority were female 63 (61.2 %) and of these 19 (18.4%) were HIV positive. The 2% participants with the Gc2 genotype were HIV and TB co infection
Conclusion: The Gc1F genotype was predominantly found in the study population with the minor alleles associated with active and latent TB states. Additionally the Gc2 minor allele was associated with HIV and active TB confection in the Ugandan population.