Hemoglobin H Disease, also known as hbh, is related to histiocytosis-lymphadenopathy plus syndrome and splenomegaly. An important gene associated with Hemoglobin H Disease is HBA2 (Hemoglobin Subunit Alpha 2), and among its related pathways/superpathways are Circadian Clock and Binding and Uptake of Ligands by Scavenger Receptors. The drugs Mitapivat and Busulfan have been mentioned in the context of this disorder. Affiliated tissues include bone marrow and bone, and related phenotypes are splenomegaly and hepatomegaly