HEREDITARY HEAT-LABILE HEXOSAMINIDASE-B - ITS IMPLICATION FOR RECOGNIZING TAY-SACHS GENOTYPES

  • 1 January 1981
    • journal article
    • research article
    • Vol. 33  (6) , 907-915
Abstract
Two pairs of alleles, at the 2 loci of hexosaminidase (HEX), segregate in an Arab inbred family: the normal and the mutant Tay-Sachs (TSD) alleles of HEX A, and the normal and a mutant allele of HEX B. Since the mutant HEX B is heat labile, no reliable identification of TSD genotypes can be obtained in its presence, as long as the proportions of HEX A and B are estimated by the routinely used heat-inactivation method. The genotypes may be correctly identified in such cases by separation of the 2 isoenzymes on ion-exchange chromatography, estimating their individual activities and calculating the ratio between them. Of the 9 genotypic combinations possible with these 2 pairs of alleles, 5 were identified in the reported family by this procedure.