Coinheritance of -3.7 Alpha-Thalassaemia Deletions Among Sickle Cell Anaemia Patients in Chhattisgarh, India

Background: Alpha (α)-thalassaemia is inherited as an autosomal recessive disorder characterised by microcytic hypochromic anaemia. In children with homozygous sickle cell anaemia (SCA), coinheritance of α-thalassemia reduces the risk of cerebral vasculopathy and alters the disease severity. This study aimed to detect the occurrence of α-thalassemia in homozygous SCA patients in Chhattisgarh state (India) and to evaluate their clinical and haematological profiles. Methods: In this study, a total of 203 well-characterized homozygous SCA patients who were diagnosed by Hb electrophoresis and Restriction Fragment Length Polymorphism (RFLP) methods were included. Genotypes of most common two deletional mutations of the α-thalassaemia genes were screened using multiplex gap-PCR. The calculation of gene frequency for α-thalassaemia mutations was done based on the gene counting method. Results: The average age at enrolment was 12.1 years for SCA. The average fetal haemoglobin was 18.7%. Out of 203 SCA patients, 9.85% and 5.4% were heterozygous (-α3.7/αα) and homozygous (-α3.7/-α3.7) for the α-thalassemia 3.7 kb deletions respectively and this distribution deviated from Hardy-Weinberg equation. There were significant differences in MCH values found in SCA with and without α-thalassaemia. Symptoms like abdominal pain and headache were significantly different between SCA with and without α-thalassaemia. Conclusions: In SCA patients coinheriting α-thalassemia, the clinical and laboratory results indicated improvement in overall clinical presentation of disease. Coinheritance of -3.7 alpha-thalassaemia deletions among sickle cell anaemia patients significantly resulted in milder clinical course.