HbD Punjab/HbQ India compound heterozygosity: An unusual association.

Abstract

Background: Haemoglobinopathies are the commonest hereditary disorders in India and pose a major health problem. Both beta thalassaemia and structural haemoglobin variants are relatively common in north western India. Here we report a 29 year old Sindhi female who was referred to us for a haemoglobinopathy work up and genetic counseling since her spouse was a classical beta thalassaemia carrier.

Method: A complete blood count was done on an automated cell counter. Haemoglobin analysis was carried out using HPLC Variant Haemoglobin Testing System.  The cellulose acetate electrophoresis was carried out [pH 8.9]. Confirmation of mutations was done by automated DNA sequencing.

Results: HPLC analysis showed four major peaks, HbA₀, a peak in the HbD window, an unknown peak [retention time 4.74 minutes] and a peak in the HbC window. The HbA₂ level was 2.2% and the HbF level was 0.7%.Cellulose acetate electrophoresis at alkaline pH, a slow moving band was seen at the HbS/D position along with a prominent band at the HbA₂ position. DNA sequencing of the ? and ? genes showed presence of the 2 hemoglobin variants :Hb D [b 121GAA à CAA] and Hb Q [a 64 AAG à GAG]. The ? globin gene was normal. The additional peak in the HbC window was due to the formation of a heterodimer hybrid.

Conclusion: Both HbD Punjab and HbQ India are relatively common in India but their co-inheritance has not been described in the country. This is the second report of compound heterozygosity for HbQ India/HbD Punjab haemoglobinopathy globally, and the first one from India.