Gene Frequencies of Human Platelet Alloantigens in Major Ethnic Groups in Rivers-State, Nigeria

Aim: The aim of this study was to evaluate gene frequencies of human platelet alloantigens among major ethnic groups in Rivers-State, Nigeria.

Study Design: A cross-sectional study.

Place and Duration of Study: Rivers State University Medical Centre, Port Harcourt, Safety Molecular Pathology Laboratory, Enugu State, Justcare clinical laboratory Port Harcourt Rivers State and University of Port Harcourt Teaching Hospital Port Harcoourt, between October 2019 and March 2020.

Methodology: The subjects consisted of apparently healthy individuals who were of Rivers State origin totaling 104 persons aged 17 to 42 years. They were under-graduate and post-graduate students of Rivers State University, Port Harcourt, Nigeria. Five major ethnic groups were considered which included Ikwerre, Ogoni, Ijaw, Etche and Ogba. Their demographic information was collected using a sample register and a questionnaire. Samples were collected from the antecubital vein. 10ml of blood was collected, 5ml was transferred into EDTA sample bottle (Ethylene diamine tetracetic acid) while 2ml was dispensed into plain bottle and labeled accordingly. Serological testing including HIV (RVS) screening, HBsag, HCV and VDRL were all done immediately after samples were collected. The remaining sample was analyzed using genotyping of Human Platelet Antigens by High Resolution Melting Curve Analysis Polymerase Chain Reaction (HRM-PCR). The melt curve analysis was done using the MicPCR software while the frequency analysis was done using Number Cruncher Statistical Software (NCSS) Version 13. Graph Pad Prism Version 8.0.2 was used to determine the statistical significance between the various HPA genotypes and the ethnic groups and p-values of <.05 were considered to be statistically significant. Results were presented in percentages, mean+/- standard deviation and in tables

Results: The results showed that HPA-4 and HPA-5 a/a and b/b were the highest among Etche (20.0% each), followed by HPA-2 and HPA-3 at 16% each for b/b and HPA-1 a/a and a/b had 10.0% and 6.7% respectively, and HPA-1 b/b, HPA-2 a/b and HPA-3 a/a had 3.3% respectively. The HPA pattern for Ijaw was highest at HPA-4 a/a (15.7%), followed by HPA-5 b/b (15.3%) and the least was HPA-2 b/b (11.4%). The pattern for Ikwerre was highest for HPA-5 b/b (20.0%) and least for HPA-4 b/b and HPA-2 a/a (0.8% each). The HPA pattern for Ogba was highest for HPA-5 b/b (20.0%) and least for HPA-3 a/a and HPA-2 a/a (0.0% each), while the pattern for Ogoni is highest for HPA-5 b/b (19.1%) and least for HPA-5 a/b and HPA-3 a/b (0.9%). The HPA alleles showed that HPA-1 a/b was highest. 42 (40.4%), followed by HPA-1 a/a 34 (32.7%) and HPA-1 b/b 28 (26.9%), and the least was 3% for HPA-2 a/b. The highest for HPA-2 was b/b, 60 (57.7%) and the least is a/a, 2 (1.9%), while the highest for HPA-3 was also b/b, 75 (72.1%) and the least was a/a 3 (2.9%). Also, HPA-4 a/a allele is the highest in its category, 85 (81.5%) and the least was a/b 9 (8.7%), while b/b, 102 (98.1%) was the highest for HPA-5 and there was none for a/b and a/a alleles.

Conclusion: The HPA alleles showed that HPA-1 a/b was highest. The highest for HPA-2 and HPA-3 was b/b. HPA-4 a/a allele was the highest in its category, while b/b was the highest for HPA-5. HPA-4 and HPA-5 a/a and b/b were the highest among Etche. The HPA pattern for Ijaw was highest at HPA-4 a/a. The pattern for Ikwerre was highest for HPA-5 b/b. The HPA pattern for Ogba was highest for HPA-5 b/b, while the pattern for Ogoni was highest for HPA-5 b/b.