Hemoglobin Genotype SD
Compound heterozygous inheritance of Hb S and Hb D mutations. Hb S occurs from substitution of valine for glutamic acid in the beta-6 position (beta6Glu>Val). Hb D generally results from substitution of glutamic acid for glutamine at beta-121 (beta121Glu>Gln); such as the Hb D-Punjab/Hb D-Los Angeles variants. There are several other Hb D variants, including Hb D-Iband where threonine is substituted by lysine at beta-87 (beta87Thr>Lys) and Hb D-Iran where glutamic acid is substituted by glutamine at beta-22 (beta22Glu>Gln).