Hb Grand Junction (HBB: c.348_349delinsG; p.His117IlefsX42): a new hyperunstable hemoglobin variant.

Hyperunstable hemoglobinopathy (HUH) [dominantly inherited β-thalassemia (β-thal)] is a relatively rare form of congenital hemolytic anemia in which mutations occur in the genes encoding for α and β chains, or both chains of the hemoglobin (Hb) molecule. We describe two Hispanic adolescents with a new unstable Hb variant (HBB: c.348_349delinsG; p.His117IlefsX42), resulting from a frameshift mutation at codons 115/116 of the β-globin gene. Both patients also have a 3.7 kb deletion on one α gene, leading to a decreased imbalance between α and β chain formation, and subsequently a milder phenotype than that seen in other hyperunstable Hb variants.