Alpha Thalassemia and Hemoglobin H Disease

Background Data:

Alpha Thalassemia and Hemoglobin H in California

Alpha thalassemia is a major public health issue throughout the world. Five percent of the world’s population are carriers for Alpha thalassemia. It is very common in California, as seen in the California Newborn Screening Program results.

Alpha thalassemia is very common in people of Asian descent in several regions of China and Southeast Asia. In addition, people of Meditteranean and Middle Eastern regions also have a high frequency. Carriers for Alpha thalassemia are healthy, and may demonstrate a mild anemia. Clinically, a carrier for alpha thalassemia is not a problem. However, a couple who are both carriers for Alpha thalassemia trait risk having a pregnancy with Alpha thalassemia major – a usually fatal in-utero disease that results in miscarriage.

Hemoglobin H, a more serious form of alpha thalassemia, may result in a significant anemia and other symptoms. There are two major types of Hemoglobin H disease; the most common type is called a “deletional” Hemoglobin H, which is milder than the non-deletional Hemoglobin H. The table below compares the laboratory and clinical findings of the deletional and non-deletional types of Hemoglobin H.

Hemoglobin H Phenotypes

Many people with Hemoglobin H may not know they have the disorder until they develop complications. California has adopted universal screening for Hemoglobin H and is the only state with such a policy. Listed below are the Hemoglobin H genotypes identified by the California Newborn Screening Program between 2006 and 2008.

Hemoglobin H Disease

from: Vichinsky E. Clinical Manifestations of Alpha Thalassemia. Cold Spring Harbor Perspectives in Medicine, September 2013.