Genotyping of Human Erythrocyte Antigens for Safe Blood Transfusion in Thalassemia Patients

Dorgam Muffed Ibraheem Yasin
ضرغام مفيد ابراهيم ياسين
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Al-Quds University
Management of β-thalassemia is a major challenge, especially in low resource countries. Blood transfusion is the mainstay treatment of patients with β-thalassemia major. However, blood transfusion is associated with several side effects including hemolytic and allergic reactions, iron overload, and transfusion-transmitted diseases. In this study, we assessed the biochemical, hematological, and hormonal parameters, estimated the prevalence of complications, studied the frequency of red blood cell alloimmunization and autoimmunization, and determined the genotype frequencies of blood group systems among transfusion-dependent β-thalassemia patients in the West Bank. Methods This study was conducted using 100 frequently transfused thalassemia patients. The patients were recruited through Thalassemia Daycare Units in five governmental hospitals patients with the highest transfusion frequency were selected for this study. A questionnaire was used to collect data regarding the basic characteristics of the patients. In addition, medical records were used to collect data regarding the complications of thalassemia among the patients. Blood samples were collected from the patients to measure biochemical, hematological, and hormonal parameters, in addition to screening and identification of antibodies and for DNA extraction. DNA samples were genotyped for Rhesus, Kell, Duffy, Kidd, MNS, Dombrock, Colton, Cartwright (Yt), Lutheran, Knops, Deigo, and Vel blood groups. Genotyping for blood groups was performed by sequence-specific primers (SSP)-PCR method. Results A total of 100 patients were included, 51% were males. The mean age among the patients was 21.9±10.9 years. The majority of the patients (60%) were recruited from Al Watani Hospital. The mean pre-transfusion hemoglobin level was found to be 7.89±0.99 g/dL and the mean serum ferritin level was 3670.42±3742.71 ng/dL. The results of liver function tests showed that 32%, 42%, and 34% had elevated ALT, ALP, and AST levels, respectively. Regarding the hormonal results,10% of the patients had subclinical hypothyroidism. The prevalence of growth hormone deficiency was 8%. Also, 8% of the patients had hypocalcemia and 70% had vitamin D deficiency. Elevated glucose levels were found among 15% of the patients. The most encountered complications were arthropathy (44%), hypogonadism (16%), and hepatic failure and delayed growth (7%). The genotyping results of the RHD blood group showed that 88% of the patients were RHD-positive whereas 7% were RHD-negative and 5% had no clear results. The allele frequencies of RHCE alleles were 0.440 and 0.560 for RHCE*C and RHCE*c, respectively, and 0.165 and 0.835 for RHCE*E and RHCE*e, respectively. Unexpectedly, for the Duffy blood group system, the null genotype (FY*02N.01/02N.01) was observed in 46% of the patients and the allele frequencies of FY*01 and FY*02 were 0.195 and 0.345, respectively. Furthermore, the allele frequencies of GYPA*M and GYPA*N were 0.585 and 0.405, respectively, and those of GYPB*S and GYPB*s were 0.275 and 0.725, respectively. The KEL*02, KEL*04, and KEL*07 allele frequencies were high among the patients in this study (0.920, 0.985, and 0.980, respectively). Furthermore, the allele frequencies of YT*A, LU*02, CO*01, KN*01, DI*B, DI*02.04, and VEL*01 were 0.940, 0.990, 0.990, 1.000, 0.980, 1.000, and 0.990. In addition, 2% of the patients had the Vel*01/-0.1 (Vel/Velnull) genotype. The rate of alloimmunization among patients was 8% and the most common antibodies were anti-E, anti-K and anti-D, and anti-C, respectively. The rate of autoimmunization was 5%. Conclusions The management of thalassemia should be based on internationally established guidelines. Understanding the frequencies of the major blood group systems other than the ABO and Rh systems is essential to provide accurate information regarding the local population’s requirements, reduce transfusion-related complications among frequently transfused patients, and facilitate the challenging task of providing antigen-negative blood for patients with multiple antibodies. Phenotyping of patients’ RBCs could have prevented the development of alloantibodies against Rh antigens C, E, and K. Furthermore, accurate testing for weak RhD among donors could also prevent alloimmunization against RhD antigens. The genotype and the allele frequencies observed among the sample of this study revealed several interesting findings that prompt further research. Keywords Alloimmunization, red cell genotyping, iron overload, beta-thalassemia, frequently transfused