Hemoglobin H disease is a type of alpha thalassemia, a genetic blood disorder that affects the production of hemoglobin, the protein in red blood cells that carries oxygen. In this condition, there is a deficiency of alpha globin chains, leading to an excess of beta globin chains that form abnormal hemoglobin known as hemoglobin H. This can result in mild to moderate anemia, fatigue, and other related symptoms. Individuals with hemoglobin H disease may experience complications such as an enlarged spleen and increased risk of infections. Diagnosis is typically made through blood tests that assess hemoglobin levels and types. Treatment may include regular monitoring and, in some cases, blood transfusions.