Heterozygous Beta Thalassemia with Segmental Duplication of chr16p13.3 Leading to Thalassemia Intermedia Phenotype: A Report of 2 Cases with Review of Literature.

Heterozygous β-thalassemia is typically asymptomatic, but when accompanied by α-globin gene multiplication, patients may exhibit clinical symptoms. We present two rare cases of heterozygous β-thalassemia where segmental duplications on chr16p13.3 led to increased α-globin gene copies, resulting in a thalassemia intermedia phenotype. One patient exhibited a novel de-novo duplication spanning 2.57 MB, while the other had a 173.8 KB duplication at the chr16p13.3 locus. These two cases are presented to underscore the significance of thorough and systematic evaluation in diagnosing rare forms of thalassemia accurately. Our study also compiles all reported cases of heterozygous β-thalassemia with large segmental duplications on chr16p13.3, leading to an excess of α-globin genes. A total of ten studies have been published in the literature so far. Importantly, the 2.57 MB segmental duplication identified in our study is a novel variant not previously documented in the literature.