Abstract
Prenatal diagnosis of hemoglobinopathies is difficult if placental blood samples are contaminated by maternal cells, because β/γ ratios exceed the normal fetal range of 0.07 to 0.15. We have shown that fetal reticulocytes have less carbonic anhydrase than adult cells, and resist NH4Cl-, NH4HCO3-mediated (ørskov) hemolysis. To test this approach in actual cases, pure fetal blood was obtained by fetoscopy from two midtrimester fetuses at risk for homozygous β-thalassemia (thal). 2.5% fetal blood was mixed with blood from the β-thal trait mothers. Samples were incubated with 3H-leucine; an aliquot was treated in the ørskov reaction. Red cell size distributions were analysed with a Coulter channelyzer. Globin chains were separated on carboxymethylcellulose columns. In the mixed samples, only small maternal cells were seen with the channelyzer. Following ørskov hemolysis, only large fetal cells were detected. In case 1, β/γ in the mixed sample was 0.42. β/γ fell to zero following ørskov hemolysis, and was zero in pure fetal blood. This fetus had thal major. In case 2, β/γ was 1.97 before and 0.04 after ørskov hemolysis; it was 0.04 in pure fetal blood. This fetus has β-thal trait. ørskov hemolysis provides pure fetal blood from samples with only 2.5% fetal cells and enables the appropriate diagnoses to be made even when low yield samples are obtained.
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Alter, B., Nathan, D., Mahoney, M. et al. 505 SEPARATION OF FETAL AND ADULT ERYTHROCYTES BY SELECTIVE HEMOLYSIS: AN AID TO PERNTAL DIAGNOSIS OF HEMOGLOBINOPATHIES. Pediatr Res 12 (Suppl 4), 448 (1978). https://doi.org/10.1203/00006450-197804001-00510
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DOI: https://doi.org/10.1203/00006450-197804001-00510