Novel dominant β-thalassemia: Hb Boston-Kuwait [codon 139/140(+T)].

Dominant β-thalassemias exhibit a hybrid phenotype of unstable hemoglobin and ineffective erythropoiesis. Most arise from heterozygous β-globin gene mutations in exons 3 or 2 and present in adulthood as thalassemia intermedia. We report a novel, de novo β-globin mutation presenting in a toddler with features of thalassemia major and chromaturia. Hemoglobin Boston-Kuwait is an elongated β-chain variant (163 amino acids) that results from a frameshift mutation caused by a thymidine insertion in codons 139/140. Hematopoietic stem cell transplant provided a successful alternative therapy for this severe form of dominant β-thalassemia.