Compound Heterozygous Hemoglobin SD Disease Presenting as Sickle Cell Crisis in Pregnancy

Hemoglobinopathies are the diverse group of inherited disorders of hemoglobin production and function. They represent the most common single gene disorder which are found in humans and are distributed in various frequencies throughout the world. Hemoglobinopathies are broadly classified as disorders that result from structurally altered hemoglobin molecules (e.g. Sickle cell anemia) or disorders that arise from numerical imbalance of otherwise normal globin chain synthesis ( β Thalassemia) 1. Sickle cell disease (SCD) is the most common inherited condition globally. Around 300000 children are born each year with SCD, two third being in Africa2. The prevalence of sickle cell gene ranges from 2-34% in India3. SCD includes homozygous (HbSS) as well as heterozygous forms of HbS in combination with other hemoglobins like hemoglobin C (HbSC), hemoglobin beta thalassemia (HbSB), hemoglobin D (HbSD), and E (HbSE). SCD occurs due to the polymerisation of abnormal hemoglobin under low oxygen tension leading to formation of fragile sickle shaped cells resulting in hemolytic anemia and vasoocclusion of small blood vessels2 (RCOG 2011). Hemoglobin D also known as Hb D Punjab is very rare in homozygous disease and results from substitution of glutamate by glutamine at codon 121 of β chain. Heterozygous state of hemolobin D may combine with sickle cell gene HbS and may manifest as hemoglobinopathy (moderate to severe HbSD) especially in north Indian states like Punjab4, 5. Pregnancy in women with sickle cell disease is associated with an increased risk of morbidity and mortality because of the combination of underlying haemolytic anemia and multiorgan dysfunction associated with this disorder. Awareness of this type of haemolytic anemia and associated obstetric complications are of paramount importance for managing this rare SCD. Multidisciplinary team approach involving obstetricians, hematologists , paediatricians and anaesthetists is required for optimum perinatal outcome. HbSD (sickle cell hemoglobin in combination with Hb D) has not been reported so far in pregnancy. We hereby report a case of heterozygous HbSD with sickle cell crisis in pregnancy secondary to infection.