Screening cord blood for sickle haemoglobinopathies in Brent

Between 1981 and 1983, 3165 consecutive specimens of cord blood were tested at the Central Middlesex Hospital for the presence of an abnormal haemoglobin: the incidence of sickle cell trait was 2.8%, of HbC trait 0.9%, and the overall incidence of an abnormal haemoglobin at birth was 6.9%. Five babies with homozygous sickle cell disease, three with HbSC, and three with either HbCC or HbC beta thalassaemia were detected. Twenty two per cent of the mothers were of Afro-Caribbean origin. The cost of the test was 30p. An H6000 blood count was carried out on 1000 consecutive cord blood samples. The mean red cell volume was 97.95 (SD 3.67) fl. Thirteen cord blood samples had a mean cell volume below 85 fl, and all contained Hb Barts. In addition, six samples with a mean cell volume between 86 and 92 fl also showed Hb Barts on electrophoresis. The overall incidence of Hb Barts was 2.1%. These results indicate that the incidence of HbSS and HbSC on neonatal screening in Brent is similar to that found in the urban areas of North America and that the number may be predicted from the number of births to mothers of Afro-Caribbean origin.