PHILADELPHIA VARIANT OF GALACTOKINASE

  • 1 January 1977
    • journal article
    • research article
    • Vol. 29  (3) , 240-247
Abstract
A polymorphism that causes black populations to have lower mean RBC [red blood cell] galactokinase activity than comparable white populations was reported. This allele is disignated the Philadelphia variant GALKP and is common in blacks and rare in whites. GALKP individuals have normal WBC [white blood cell] GALK activity, in contrast to the half normal WBC GALK activities of heterozygotes for the allele (GALKG) that causes the galactokinase-deficient form of galactosemia. In 1 family 2 sisters heterozygous for both GALKG and GALKP alleles were found. These individuals have 50% normal WBC CALK activity and less than 50% normal red cell activity. The latter finding indicates that the 2 variant GALK alleles additively affect RBC activity. The WBC results suggest that the low activity of GALK in RBC of individuals with the GALKP allele is due to its relative instability. No evidence for such instability was obtained from studies of high reticulocyte bloods or RBC fractionation. The GALK in WBC from GALKP individuals did not have altered electrophoretic migration.