Characterization of unusual hexosaminidase A (HEX A) deficient human mutants.

Two families with unusual hexosaminidase A (HEX A) mutations are described. In one, the proband had the Tay-Sachs disease phenotype with considerable HEX A activity. In the second, the proband was phenotypically normal with absent HEX A activity.

Electrophoretic study of human ribosomal core proteins: evidence for selection against variation.

Ten human ribosomal core proteins examined electrophoretically showed significantly less polymorphic variation than expected on the basis of other protein systems studied. This implies that selective forces may restrict variation at these loci. Variation in common multigenic traits must be determined by a combination of common alleles.