Title: Gene Frequencies of Human Platelet Alloantigens among Some Major Ethnic Groups in the Niger Delta region of Nigeria

Biography:

Professor Zaccheaus Awortu Jeremiah is a Professor of Haematology and Blood Transfusion Science at the Rivers State University, Port Harcourt. He holds the Doctor of Philosophy (Ph.D.) in Haematology and BTS, Fellow of the Institute of Biomedical Science (FIBMS) London, Fellow of the Royal College of Pathologists (FRCPath) London, and Fellow of the West African Postgraduate College of Medical Laboratory Science ( FWAPCMLS). He is currently the Regional Chair of the Haematology Faculty in WAPCMLS.

Abstract

Statement of the Problem: Human Platelet Alloantigens (HPA) expresses Polymorphisms that arise from single base pair substitutions in alleles (their alleles are designated as ‘a’ or ‘b’ which usually occurs in pairs of homozygous or heterozygous forms) and lead to changes in amino acids of glycoproteins expressed on platelets. In a previous study, alloantibodies to human platelet antigens (HPA) were carried out using the GTI PakPlus solid phase enzyme-linked immunosorbent assay (ELISA) method. This present study was a follow-up to the serological study aimed at the molecular determination of gene frequencies of human platelet alloantigens among major ethnic groups in the Niger Delta region of Nigeria.

Materials and methods: This was a cross-sectional, randomized research. Five major ethnic groups were considered which include Etche, Ikwerre, Ijaw, Ogba, and Ogoni. A total of 104 participants between the ages of 16 – 42 years were recruited for the study of which 59 of the subjects were males and 45 were females. They were undergraduate and post-graduate students of Rivers State University, Port Harcourt, recruited during their pre-admission medical examination into the University. They were apparently healthy individuals who were serologically screened, and negative for HIV 1 &11, HBsAg, HCV, and VDRL (syphilis). In the study 25 of the subjects were of Ikwerre origin, 22 from Ogoni, 24 from Ijaw, 6 from Etche, and 22 from the Ogba region. Ten milliliters (10 ml) of blood was collected from each of the participants using standard venipuncture while maintaining good laboratory practice and quality control. HPA genes (genotype) were determined using the state-of-the-art Magnetic induction Cycler MiC-PCR Real-Time PCR System Australia. Data generated were analyzed using melt curve analysis in the micPCR software while the frequency distribution was done using Number Cruncher Statistical Software (NCSS) Version 13.0.  P values less than 0.05 was considered statistically significant.

Findings: Frequency distribution of HPA gene typing in the overall population shows that HPA 1a/a (32.70%) HPA 1 a/b (40.40%) HPA 1b/b (26. 93%), HPA 2 a/a (1.9%) HPA 2a/b (40,42%) HPA 2b/b (57.7%), HPA 3a/a (2.9%) HPA 3a/b (25.0%), HPA 3b/b (72.1%). HPA 4a/a (81.7%), HPA 4a/b (8.7%), HPA 4 b/b (9.6%), HPA 5a/a was absent, HPA 5a/b (1.9%) and HPA 5b/b (98.1%) For the various ethnic groups; in Etche and Ijaw HPA 4a/a and HPA 5b/b were the most predominant, interestingly this was also the case in Ogba, Ikwerre and Ogoni.

 Conclusion and Clinical Significance: Homozygous ‘b’ was more prevalent among all the populations, followed by homozygous ‘a and heterozygous a/b. HPA-5 b/b is most prevalent in the general population while the HPA-5a/a was completely absent. Since Human platelet antibodies are often implicated in conditions such as alloimmune thrombocytopenia(NAIT), Idiopathic thrombocytopenic purpura(ITP) and platelet refractoriness, a molecular study to determine the human platelet genes in this part of this world became necessary hence this study.