Gene frequencies of ABO and Rh(D) blood group alleles in Lagos, South-West Nigeria

Abstract

Background: It has been well documented that the ABO and Rhesus remain clinically the most significant blood group systems. There is limited information on the gene frequency of the ABO and Rhesus blood groups from Lagos, South-West Nigeria. Data from this study will be of immense use to the geneticists, biologists, blood transfusion services policy maker and clinicians.
Aim of this study: This study aims to provide descriptive information on the genetic composition and variation of population in Lagos State, Nigeria, with respect to blood group and Rhesus factor contributing to the existing knowledge.
Subjects and methods: This study investigated the gene frequencies for the ABO and Rh(D) alleles in a population consisting of different ages in Lagos, Nigeria, over a period spanning 12 years (1998–2009). The 23,832 and 23,764 individuals were typed for ABO and Rh blood groups, respectively. We analyzed the genotypic and allelic frequencies based on Hardy–Weinberg equations. Chi-square goodness-of-fit statistic was calculated to compare observed and expected frequencies and to investigate heterogeneity between years.
Results: 5504 (23.1%), 5072 (21.3%), 647 (2.7%) and 12,609 (52.9%) were blood groups A, B, AB and O, respectively. Over the period of this study, we observed an overall trend of ABO blood group was O> B > A> AB in both males and females. We also observed that blood group O was the most encountered phenotype while group AB was the least phenotype encountered among the studied population in both genders. This distribution differs significantly (p<0.05) from those expected under the Hardy–Weinberg law. With regard to the Rh blood group, individuals with Rh positive (DD and Dd) were 0.69 and 0.28. Rh negative (dd) was 0.03. This also showed that Rh(D) positive was the most phenotype observed in this study. This distribution do not differ significantly (p>0.05) from those expected under the Hardy–Weinberg law.
Conclusion: Our results demonstrate that there exist genetic variability and polymorphism as regards ABO and Rh blood group among the population sampled. These findings would be useful to geneticists and clinicians when planning to address future health challenges relating blood transfusion and marriage counseling.

Keywords: Blood groups; Gene frequencies; Rhesus; Alleles