HbQ-India in a Sindhi family: an uncommon hemoglobin variant.

Hemoglobin Q-India is a very rare alpha-chain structural variant caused by the mutation AAG-->GAG (Asp-->His) in the position of codon 64 of the alpha1 gene. Usually it presents in the heterozygous form with electrophoretic mobility in the position of hemoglobin S (HbS) at alkaline pH along with the double bands of HbA2. High-performance liquid chromatography (HPLC) retention time of 4.