1. The present paper describes an apparently white family in which a few members suffered from homozygous and heterozygous hemoglobin C disease. Since the paternal great grandfather and the maternal grandfather of the patients examined were in a family relation of the first order, it is surmised that the hemoglobin C was derived from the same homozygous negroid (?) ancestor. Besides its occurrence in this family Hb-C is also found in a colored family from the same island (Curaçao).
2. Hemoglobin C shows, in addition to abnormal electrophoretic mobility, three other more or less specific properties:
a. During chromatographic examination carried out with the aid of the cation exchanger Amberlite IRC 50 (XE 64), a citrate citric acid buffer at pH 6 and sodium ion concentration of 0.15, COHb-C displaces itself noticeably slower than the three other forms of hemoglobins (S, A and F).
b. The solubility of the COHb-C in a phosphate buffer pH 6.5 of various concentrations is significantly less than that of COHb-S, COHb-A and COHb-F. The reduced form of hemoglobin C does not show this property; the solubility of this is practically the same as that of reduced adult hemoglobin.
c. A comparison of the amino acid composition of hemoglobin C and hemoglobin A, S and F, shows that COHb-C contains a higher number of lysine and perhaps histidine residues. This increase amounts to four residues per mol. for lysine and one residue per mol. for histidine. The possible connection between the more basic character of the proteins and the abnormal behavior in the electrophoretic and chromatographic experiments is discussed.
3. The results obtained with five experimental methods (electrophoresis, alkali denaturation, chromatography, salting-out experiments, and amino acid composition determination) all seem to indicate that in the homozygous form of this disease only the abnormal Hb-C is present. None of the other three hemoglobins (A, S and F) were shown to be present in determinable amounts.
4. In addition to the electrophoretic abnormalities, the above three properties may be of importance in the characterization of this abnormal hemoglobin.