An Inhomogeneous Fœtal Hæmoglobin Variant (the Texas Type)

Abstract

DURING a survey of fœtal types of hæmoglobin, the cord blood samples of 368 White and 1,192 Negro infants were examined, and a possibly new fœtal variant was found in one White and three Negro infants. All four babies were born at term, and all appeared healthy. In their hæmolysates, the F hæmoglobin values, by the method of alkali denaturation¹, ranged between 68 and 82 per cent, and in zone electrophoresis there was about 15 per cent or less, each, of hæmoglobin A and the variant. Two of the Negro babies were siblings, and the samples from the younger of these (L. C. W.) and from the unrelated Negro infant (W. T.) were examined in detail. In paper electrophoresis, barbital buffer, pH 8.6 (Fig. 1) the variant, tentatively called ‘Texas’, forms a broad band with a suggestion of two components, moving slightly more cathodally than hæmoglobin C, and in agar electrophoresis, citrate buffer, pH 6.2, it moves between hæmoglobins F and A (Fig. 2). In starch gel electrophoresis in tris borate buffer, pH 8.6, the mobility is similar to that of hæmoglobin C, as is also the case in starch block electrophoresis, barbital buffer pH 8.6. In these latter two methods a small amount of a hæmoglobin fraction of the mobility of Bart's was detectable in each hæmolysate. The Texas variant, eluted from the starch block, was examined with respect to its rate of alkali denaturation, by the method of Jonxis and Visser², and the values obtained were similar to those of a mixture of about 0.75 A and 0.25 F. In its ultra-violet absorption spectrum, as determined in the Beckman DU spectrophotometer, there were 2 tryptophan fine-structure bands, one at a wave-length of 288–289 mµ and the other at 290–291 mµ.