DEVELOPMENTAL HEMOGLOBIN ANOMALIES IN A CHROMOSOMAL TRIPLICATION: D 1 TRISOMY SYNDROME

Abstract
Hb-Gower 2 appears to be a normal embryonic hemoglobin detectable in very young human embryos. This hemoglobin was found to persist in small amounts in 5 newborns with D1 trisomy. These infants also carried increased amounts of Hb-[gamma]4. Hb-Gower 2 is a tetramer with 2 normal a chains. It is suggested that the non-a-chains differ from the other hemoglobin chains by more than one amino acid substitution and that they represent a hitherto undescribed, biochemically and functionally distinct chain, the c chain. Three older children with D1 trisomy had slightly elevated amounts of Hb-F. Presumably, genetic elements which, directly or indirectly, affect the synthesis of [gamma] and the postulated chains are located on the chromosome triplicated in D1 trisomy.