ß-globin gene cluster haplotypes and clinical severity in sickle cell anemia patients in southern Brazil

Abstract

Hematopoietic stem cell transplantation (HSCT) has emerged as a curative strategy for sickle cell anemia (SCA); it is necessary to find markers of SCA clinical severity to spare those SCA patients whose clinical course is mild from the morbidity and mortality associated with HSCT. Haplotypes have been correlated with the severity of clinical manifestations in SCA patients, and fetal hemoglobin (HbF) and socioeconomic status (SeS) have also been described as negative factors. We studied these factors and their impact on clinical manifestations in a population of Southern Brazilian patients attending the Center for Sickle Cell Anemia at Hospital de Clínicas de Porto Alegre/RS, Brazil. Clinical severity was defined as two or more veno-occlusive episodes per year. The βS haplotypes were determined by PCR in 75 SCA patients. Among the 150 βS chromosomes analyzed, 99 (66%) were identified as Bantu (Ban), 41 (27%) as Benin (Ben), and 10 (7%) as other haplotypes. Most patients in our sample (62.7%) belonged to lower SeS groups, precluding meaningful statistical analysis of SeS impact on clinical severity. There was no correlation between haplotypes or HbF level and SCA clinical severity. Gene polymorphisms and environmental issues have to be taken into consideration.