Fetal hemoglobin levels and beta s globin haplotypes in an Indian population with sickle cell disease

ABSTRACT

To further explore the cause for variation in hemoglobin F (HbF) levels in sickle cell disease, the á globin restriction-fragment length polymorphism haplotypes were determined in a total of 303 (126SS, 141AS, 17Sá§, 7Aá§, and 12AA) Indians from the state of Orissa. The ás globin gene was found to be linked almost exclusively to a ás haplotype (+++-++-), which is also common in Saudi Arabian patients from the Eastern province (referred to as the Asian ás haplotype). By contrast, the majority of áA and ᧠thalassemia globin genes are linked to hoplotypes common in all European and Asian populations (+-----[+/-];--++-++). Family studies showed that there is a genetic factor elevating HbF levels dominantly in homozygotes (SS). This factor appears to be related to the Asian ás globin haplotype, and a mechanism for its action is discussed. There is also a high prevalence of an independent Swiss type hereditary presistance of fetal hemoglobin (HPFH) determinant active in both the sickle cell trait and in sickle cell disease.(AU)