sickle cell disease: a single gene mutation with varied presentations

Sickle cell disease is one of the commonest severe monogenic disorders seen worldwide. hemoglobin s (hb s) is the result of a single base-pair change, thymine for adenine, at the sixth codon of the β globin gene. this change encodes valine instead of glutamine in the sixth position in the β globin molecule. in the united states, sickle cell disease occurs in african americans at a rate of 1: 396 births and in hispanics at a rate of 1: 36,000 births. in the uk, the prevalence is 1:2000 live births. in india scd gene frequency varies from 2 to 14 % of at risk population and is as common as thalassemia, but less highlighted, due to the predominantly underprivileged, tribal population of central india (vidharbha, marathwada, m.p., ap, west-odisha., chhattisgarh and gujrat).