Screening Test Recommended for Heritable Blood Disorder

A blood test has been recommended for screening newborns or infants for all forms of an inherited blood disorders as this may reduce morbidity.

The hemoglobinopathy is known as Hemoglobin H disease or Alpha Thalassemia and is diagnosed by a variety of tests including high performance liquid chromatography (HPLC). Samples containing more than 25% hemoglobin Bart's should be selected for confirmatory testing.

Over a 15-year period, scientists at the Children's Hospital Oakland, (CA, USA), observed and tested 86 patients, of whom 23 had hemoglobin H Constant Spring mutation (HCS). Diagnosis was confirmed by thin-layer isoelectric focusing, and specific α-globin gene deletions or mutations were identified by multiplexed gap-polymerase-chain-reaction assay. Patients with hemoglobin H have moderately severe anemia because of gene defects leading to insufficient production of hemoglobin. The disorder does not usually cause significant health problems, except in cases of HCS, a severe form of the disease, which often results in life-threatening anemia.

The study provided a previously undocumented natural history of the disease in young children. The patients with HbH exhibited relatively normal growth and development without needing blood transfusions, but patients with HCS were at high-risk for life-threatening anemia even during infancy. There were significant differences in hemoglobin levels between the HbH group and the HCS group and the absolute reticulocyte count and bilirubin level were consistently higher in patients with HCS.

A diagnosis of HCS avoids expending precious time, which could save a young life and money trying to diagnose the problem. The study also demonstrated that hemoglobin H is not restricted to the traditional Asian ethnic populations. Although 81% patients studied had an Asian background, 5% were Hispanic, 3% were African American, and 10% had mixed ancestry.

The study shows that the advanced DNA testing at Children's Hospital Oakland can predict the course of the disease during childhood, which helps to ensure proper treatment for all patients. Hemoglobin H disease arises from the deletion of three of four α-globin genes and HCS is caused by the deletion of two α-globin genes and the Constant Spring mutation. In California, one in 10,000 newborns is diagnosed with hemoglobin H disease. The study was published on February 24, 2011, in the New England Journal of Medicine (NEJM).

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Children's Hospital Oakland