Profiling of 35 Cases of Hb S/Hb E (HBB: c.20A>T/HBB: c.79G>a), Disease and Association with α-Thalassemia and ß-Globin Gene Cluster Haplotypes from Odisha, India.

ABSTRACT

Hb S/Hb E (HBB c.20A>T/HBB c.79G>A) is an uncommon variant of sickle cell disease resulting from coinheritance of Hb S and Hb E. Clinico-hematological and biochemical parameters of 35 cases of Hb S/Hb E disease were studied and compared with 70 matched cases of homozygous sickle cell disease (Hb SS) and Hb S/ß-thalassemia (ß-thal) with IVS-I-5 (G>C) (HBB c.92+5G>C). The influence of α-thal and that of of ß-globin gene cluster haplotypes among Hb S/Hb E disease was also studied. Statistical analysis was done using GraphPad InStat version 3.06. Of the 35 cases, 20 (57.14%) had a moderate clinical presentation. Mean lactate dehydrogenase (LDH) level, vaso-occlusive crises (VOCs) per year, and annual blood transfusion requirements were significantly lower in Hb S/Hb E cases than in the other two groups. The hemoglobin (Hb) and packed cell volume (PCV) levels were significantly high in Hb S/Hb E cases with α-thal and these cases were associated with microcytic-hypochromic anemia. α-Thalassemia did not influence clinical presentation in Hb S/Hb E cases. The ß-globin gene cluster haplotypes of 70 alleles of Hb S/Hb E revealed an association of five typical haplotypes [Arab-Indian (A-I), Benin, Bantu, Cameroon and Senegal] in 95.71% cases. Hb S/Hb E disease exhibit asymptomatic to moderate phenotypic expression. However, further in-depth studies on Hb S/Hb E will help in reducing the disease burden especially in high-risk countries like India.