We present case histories of three patients who had β-thalassemia (β-thal) trait with 'unusual severity' managed as β-thal intermedia (β-TI) where the basis of disease severity could not be explained with routine hematological and genetic investigations. The clinical diagnosis of 'thalassemia intermedia' was justifiable as they had a β-thal mutation and disease severity that did not fit in with either β-thal trait or with β-thal major (β-TM). As mutations of α, β, and γ genes could not explain the unusual severity of the disease, further analysis with next-generation sequencing (NGS) for red cell diseases was carried out, which led to the diagnosis of coexisting membranopathies. This case series highlights the inherent difficulty in the diagnosis of β-TI with certainty in some patients where the genetic basis is not clear-cut.
Keywords: phenotypic diversity; red cell membranopathy; β-Thalassemia intermedia (β-TI).