Publication:

Molecular Characterization of Red Blood Cell Variants Among Blood Donors at The National Testing Laboratory Nairobi –Kenya Blood Transfusion Service

A genetic variant is an alternative nucleotide located at a specific region within a gene. To date, 48 genes encoding human red cell blood systems have been recognised. Variants within these genes encode for alleles, which can be highly polymorphic. Red cell nucleotides exhibit diversity among different populations worldwide. In Africa, there is limited information on the distribution and population frequency of red cell variants. In Kenya, there lacks red cell variant and blood group allele data to support with the investigations of alloimmunisation and management of rare blood types. This research therefore, pursues to generate molecular information of selected red cell variants in donated blood samples at the Kenya National Blood Service testing Laboratory. The rationale of the study was to generate molecular data on ABO, RH, MNS, Dantu, Kell, Kidd, Duffy red cell variants and predicated phenotypes. Also to contribute towards construction of a biobank (gene base/gene bank repository). The study design was experimental. Blood collected from donors for routine testing at the National Testing laboratory Nairobi of National Blood Service -Kenya was utilised. Next generation sequencing for molecular characterization of red cell variants was carried out using a custom panel on an Illumina MiSeq platform. Descriptive statistics were used in data analysis and results displayed in tabular formats. The results; ABO, O: 52%, B: 14%, A1:12%, A2: 5.6%, Ax 4.6%, B3: 4.6%, weak A2:2.3% and the rest A1B or A2B were below <1%. RHD gene: 30% genotyped as D+ 26% as D-, 10.2% as weak D, 4.6% as Del, with a number of other weak variants reported including 1% DAU6. RHCE gene:28% were c+e, C+V+VS+c+e+hrB+(17.6%),C+c+e+(14%),V+VS+c+e+hrB+(13%),C+V+VS+c+hrB+(11.1 %),JAL+Partial_c/VS+WhrB+W⸍‫־‬hrS+W⸍ (6.5%).MNS system: 40% genotyped as N+s+, M+Mc+N+ s+(36.1%),M+s+(21.3%) and M+Mc+N +S+s+ (2.8%). KEL system: 76.9% genotyped as k+, (KEL2) Jsa (KEL6), Jsb (KEL7) at 15.7%, K+k+ (22%). Kidd system genotyping predicted 28% were Jk (a+b-), 24.1% Jk (a+b+), 22.2% Jk (a+b-), 17.6% as Jk (a+Wb+), 6.5% as Jk (a-b+),with 1.9% as Jk (a+ Wb-). In the Duffy system, the null phenotype Fy (a-b-) genotype was the most common with ~90% of samples observed with this genotype. There was limitation in the characterization of Dantu variants because there are three different variants that are associated with Dantu and is not yet determined which one is in Kenya; thus, this will require more data and research to establish a reference gene to align them. A number of novel non-synonymous variants were identified in the dataset, which may be of potential immunologic significance in blood groups systems such as KEL and Augustine. This study has revealed a distribution of red cell variants for randomly selected Kenyan donors, in addition, valuable knowledge is presented in relation to rare and unusual variants as a basis for future research in Kenya. The study provides tools for extended typing in blood banks as a basis for improved transfusion practices and possibly for development of a genomic reference library.