Postnatal Fetal and Adult Hemoglobin Synthesis in D₁ Trisomy Syndrome

Studies were carried out during the neonatal period in three infants with D₁ trisomy syndrome to measure the proportion of fetal and adult hemoglobin being synthesized. These values were compared on the one hand to those previously reported from samples obtained from cord blood of normal newborn infants ranging from 25 to 43 wk gestation, and on the other hand to those values determined in critically ill infants of the same postconceptional age. Blood samples were incubated in an amino acid mixture containing ¹⁴C-leucine followed by column chromatography on DEAE Sephadex for separation of fetal and adult hemoglobin fractions. Liquid scintillation counting was carried out on the hemoglobin fractions. In infants with the D₁ trisomy, the delay in transition to adult hemoglobin synthesis was 7-8 wk behind that expected for their postconceptional ages, and there was no accelerated transition to adult hemoglobin synthesis in the one case studied beyond the early neonatal period. Unlike the D₁ trisomy infants, the critically ill controls showed no retardation in their transition toward adult hemoglobin synthesis. The duplication of the genes in one of the 13-15 chromosome groups is a factor that delays the developmental synchrony of hemoglobin synthesis.