Table 1 Types of SCD and their nature [27, 34, 43, 56, 93]
From: Recent progress in the treatment of sickle cell disease: an up-to-date review
Severe sickle cell disease | |
β6Glu > Val/β6Glu > Val (HbS/S) | The most prominent SCD is the common form |
Thalassemia (HbS/β°) | This is widely seen in the eastern Mediterranean region and India mostly |
Thalassemia (Severe HbS/β+) | This is widely seen in the eastern Mediterranean region and India mostly(1% to 5%) |
β6Glu > Val/β121Glu > Lys (HbS/OArab) | The Balkans, the Middle East, and North Africa are mostly seen; very rare |
β6Glu > Val/β121Glu > Gln (HbS/D Punjab) | It occurs worldwide but in northern India it is principal |
β6Glu > Val/β6Glu > Val/β, β73Asp > Asn (HbS/C Harlem) | It is clinically severe but looks like HbSC electrophoretically; β-globin gene with double mutation; usually very rare |
β6Glu > Lys/β6Glu > Val, β23Val–Ile (HbC/S Antilles) | β-globin gene is double mutated which results in severe SCD with co-inhabitation with HbC; usually very rare |
β6Glu > Val/β87Thr > Ile (HbS/Quebec-CHORI) | Only two number of cases have been described with this form |
Moderate sickle cell disease | |
β6Glu > Val/β6Glu > Lys (HbS/C) | Mostly 25–30% of cases of the sickle cell disease are found in African populations |
Moderate thalassemia (HbS/β+) | Mostly found in the region of eastern Mediterranean |
βA/β6Glu > Val, β121Glu > Lys (HbA/S Oman) | It is The most dominant form of the sickle cell disease which is caused by a duple mutation in the β-globin gene |
Mild sickle cell disease | |
Mild HbS/β++ thalassemia | Mostly prominent in African populations |
β6Glu > Val/β26Glu > Lys (HbS/E) | HbE dominates in the southeast region of Asia and so HbSEis uncommon, and frequency is usually increasing with migration of population |
βA/β6Glu > Val, β68Leu/Phe (HbA/Jamaica Plain) | The very dominant form of the sickle cell disease; double mutation causes low oxygen affinity carrying Hb |
Very mild sickle cell disease | |
HPFH/ HbS/ | This group of disorders is generally caused by deletions of the larger β-globin complex of gene and found typically in fetal Hemoglobin at a concentration of 30% |
other Hb variants | Here HbS is usually co-inherited with so many other variants of Hb |