GSTM1 and thalassemia: Haemoglobin electrophoresis findings consistent with Hb H Constant Spring disease co-inherited with Hb E. Molecular genetic testing confirmed compound heterozygosity for the South East Asian (SEA) deletion and Hb CS mutation along with heterozygous Hb E. This case highlights the importance of considering complex haemoglobinopathies such as Hb AE Bart’s disease in patients presenting with anemia, especially in regions with a high prevalence of thalassemia.