Abstract

A 25-yr-old Indian (Asiatic) woman investigated for a life-long anemia was found to have a hitherto undescribed structural hemoglobin variant α2Aβ222-glu→gln, which was found independently and designated Hb D Iran by Rahbar in members of a family from Iran. In the present case, Hb D Iran was found in association with high A2 thalassemia. The replacement of glutamic acid by glutamine at β 22 (helical residue B4) was demonstrated by thin-layer chromatography after automated Edman sequencing. This is the fourth substitution to be described at β 22; the previous substitutions were (1) G Coushatta (ala); (2) E Saskatoon (lys); (3) G Taipei (gly). Helical residue B4 is an external residue, does not participate in α-β or protein-heme contacts and hemoglobin D Iran resembles Hb A in visible spectra, O2 equilibria in dilute solutions and heat stability. Since the propositus and her mother who was also heterozygous for β thalassemia had similar degrees of anemia, no interaction between this variant and β thalassemia was evident. The presence of this Hb variant in Iranians and in Western Indians may reflect the migrations of populations in these areas centuries ago.

This content is only available as a PDF.