Sickling Disorder Caused by Co-Inheritance of Hemoglobin Maputo and Hemoglobin S: Case Report and Review of the Literature

We report a family study wherein the index patient, a 6-year-old Mozambican female, was diagnosed with compound heterozygous HbS and Hb Maputo. She presented with acute pain, swelling and tenderness in the right fronto-temporal region of the skull, which raised suspicion of sickle cell disease (SCD). Prior to this presentation, a two-year history of vague clinical symptoms (viz., periodic fever, joint pain and abdominal pain) was obtained. Both parents were clinically asymptomatic. Hemoglobin separation studies were performed using hemoglobin electrophoresis and high performance liquid chromatography. Next generation sequencing technology was employed for gene sequencing analysis of globin genes. Both parents were also fully investigated. Hemoglobin separation studies on the index patient detected two hemoglobin variants that were identified on gene sequencing analysis as HbS and Hb Maputo. The mother and father were demonstrated to have heterozygous HbS and Hb Maputo, respectively. The α globin genes in all the family members had a normal wild type configuration. Conclusion: Hb Maputo in the heterozygous state is an uncommon β chain variant that is clinically silent whereas co-inheritance of Hb Maputo and HbS causes a sickling disorder with vaso occlusive disease.