Frequency and genotyping of alpha thalassemia in individuals undergoing premarital screening.

OBJECTIVE: To evaluate the frequency of alpha thalassemia and detect mutations in the alpha genes in individuals undergoing premarital screening. METHODS: The cross-sectional study was conducted at King Fahad Central Hospital, Jazan, Saudi Arabia, from January 2018 to May 2019, and comprised blood samples of individuals visiting the premarital screening clinic. The samples were analyzed for complete blood counts and haemoglobin electrophoresis. Molecular analysis of samples suspected for alpha thalassemia was done using alpha-globin StripAssay kit. Data was anlaysed using SPSS 20. RESULTS: Of the 3,970 samples analysed, 1,859(46.83%) were from males and 2,111(53.17%) from females. The overall frequency of suspected alpha thalassemia was 4.43% based upon haematological parameters including complete blood count and haemoglobin electrophoresis. Overall, 80 suspected samples were selected for genetic analyses, and, of them, 76 (95%) were positive for deletional and non-deletional mutations of alpha-globin genes, while 4 (5%) were negative for any of the 21 mutations tested. CONCLUSIONS: Alpha thalassemia was found to be highly prevalent in the study area.

Prevalence of A2 and A2B Subgroups and Anti-A1 Antibody in Blood Donors in Jazan, Saudi Arabia.

PURPOSE: A2 and A2B are rare phenotypes of the ABO blood group system. Some individuals with A2 and A2B may have anti-A1 antibodies that may be clinically significant or insignificant. The aim of this study was to determine the frequency of A2, A2B phenotypes and anti-A1 antibodies in blood donors in Jazan, Saudi Arabia. This study also evaluated the reactivity potential of anti-A1 antibodies. MATERIALS AND METHODS: Blood samples collected from 446 blood donors were typed for ABO (cell and serum grouping) and Rh D. Individuals with blood group A and AB were further subtyped by testing with anti-A1 lectin. In addition to the serum grouping using A1 red cells, A2 and A2B individuals were screened for the presence of anti-A1 in their sera against A1 red cells at 4°C, 22°C and 37°C to determine the thermal amplitude of the reacting anti-A1 antibody (if present). RESULTS: Among A and AB, A1 was the commonest phenotype (20.2%, n=90 out of 446) while A1B was found to be 1.8% (n=8) among AB phenotype. A2 and A2B were found to be 2.2% (n=10) and 0.9% (n=4), respectively. Only one individual with A2B blood type showed cold reactive anti-A1 antibody, the strength of which was 32. CONCLUSION: A2 and A2B were the rarest among ABO phenotypes in the studied population. Although rare, anti-A1 antibody is not so uncommon. Care shall be taken during routine ABO grouping especially in cases of mix-field or weak positive reactions in A and AB phenotypes.