Screening for sickle cell disease on dried blood: a new approach evaluated on 27,000 Belgian newborns.

SETTING: Early diagnosis of sickle cell disease decreases morbidity. However, cost-effective screening programmes are not yet available. METHODS: We explored the feasibility of systematic screening performed on dried blood harvested from five-day-old newborns. RESULTS: A total of 27,010 samples were collected in Belgian maternity units between June 2003 and February 2005, and the presence of haemoglobin (Hb) C or S in the eluted blood was examined by an enzyme-linked immunosorbent assay (ELISA) test performed with a monoclonal antibody detecting both mutated forms. As this antibody slightly cross-reacts with Hb A, better specificity is achieved if the test is performed not later than day 5. Among the 27,010 samples, 132 (0.49%) were positive. Molecular biology tests performed on dried blood from positive samples showed that 106 of these babies were heterozygotes for the Hb S mutation and three were heterozygotes for the Hb C mutation, while three newborns were SS homozygotes (0.011%). Seventeen samples (0.063%) were false-positives as we could not detect any mutation. CONCLUSIONS: We have developed a new immunological approach in the field of haemoglobinopathy neonatal screening. This ELISA test is cheap (0.2 euro/test or 1800 euro/detected SS homozygote) and could be centralized. Its cost-effectiveness in the whole Belgian population is comparable with that of screening for phenylketonuria or congenital adrenal hyperplasia. Further improvements should obviously be achieved in order to better discriminate heterozygotes and homozygotes, but the accessibility and the low cost of the test are relevant arguments for the screening extension in a wide range of countries, especially in Central Africa.