Abstract
Five hundred and thirty-nine randomly selected umbilical cord blood samples (449 Negroes and 90 Caucasians) were studied. Observations were made on 15 babies with abnormal hemoglobins until 3 to 19 months of age.
Hgb D was found in high concentration, approximately 27 per cent, in the cord blood of two newborn infants. The mobility of the fetal Hgb D by starch block and paper electrophoresis (pH 8.6) was slower than that of the Hgb D found in the parents. The cord blood D had many characteristics of a fetal hemoglobin and even though the abnormality was in the alpha chain, the hemoglobin behaved similarly to normal fetal hemoglobin in respect to alkali denaturation, mobility on agar electrophoresis (pH 6.2) and on resin column chromatography. It appears that gamma chains influence the mobility of the fetal form of Hgb D α on these two supporting media. The N-terminal amino acid was glycine following one hour of acid hydrolysis; valine was present in the 18 hour acid hydrolysate. Observations made on "fingerprints" of tryptic digests of hemolysates of Hgb D indicated that peptide 3, contained in the alpha chain, had moved from the neutral core to overshadow peptide 9. One-dimensional electrophoresis of tryptic digests of Hgb D displayed a peptide between the neutral zone and peptide 10 which was not seen in digests of Hgb A. The peptide gave a strong staining reaction for histidine. Peptides 3 and 9 are α chain peptides; their involvement provides strong evidence for an alpha chain abnormality in Hgb D αSt. Louis.
Forty-seven (10.1 per cent) Negro babies had Hgb S in their bloods. The amount ranged from 1.7 to 8.5 per cent of the total hemoglobin and 0.9 to 13.0 per cent of the erythrocytes sickled after treatment with metabisulfite. Five newborns with sickle cell trait were regularly observed. The amount of Hgb S gradually increased to adult levels by 3 to 8 months of age. Nine newborn infants (2.0 per cent) had Hgb C in their cord blood. The concentration of Hgb C approached the maximum value by 6 months of age in one infant observed over a period of one year.
The amount of Hgb F in 143 unselected cord bloods ranged from 60 to 96.7 per cent (mean 77.8); the mean value for 134 full term babies was 77.1 and for 9 prematures 81.7 per cent. No correlation was found between the amount of Hgb F and the birth weight, between boys and girls, between Caucasian and Negro, nor between those with normal and those with abnormal hemoglobins.
The characteristics of a "fast" Hgb, Hgb γ4 ("Bart’s"), found in cord blood were described. The concentration of Hgb γ4 in 10 bloods quantitated ranged between 2.3 and 12.4 per cent of the total hemoglobin. Of nine infants who were routinely examined, three had other abnormalities, Hgb S and Hgb D, and hereditary elliptocytosis, and six appeared to have no associated blood dyscrasia (except for possible iron deficiency detected at one year in two) and were normal and healthy.
Hgb A2 in 90 random cord blood specimens ranged from 0 to 1.8 per cent of the total hemoglobin. There was no correlation between the amount of Hgb A2 and Hgb A1, Hgb F and birth weight. Other minor components of hemoglobins were also described.
The conclusions made from the observations were: (1) at birth the rate of synthesis of alpha chains appears to be already at maximum, (2) the synthesis of beta chains was low, and (3) the gamma chain production was active as indicated by polymerization in some apparently normal infants. However, slow synthesis of alpha chains could not be ruled out as a cause for gamma chain tetramers.
