SERUM BETA-HEXOSAMINIDASES IN PREGNANCY

Serum contains several hexosaminidase forms. Two, HEX A and HEX B, migrate in both DEAE cellulose and isoelectric focussing systems like their tissue counterparts. A major group of serum hexosaminidases migrate in an intermediate position. These forms, collectively named HEX I, increase during pregnancy and obscure carrier detection for Tay-Sachs and Sandhoff's disease. Using DEAE-cellulose chromatography, HEX A, I, and B, can be clearly separated. In normals, activity ratios of A/B are 4.03 ± 1.33. During pregnancy the ratio falls slightly to 3.01 ± 1.08. In Tay-Sachs heterozygotes the ratio is only 1.08 ± 0.35 amd falls during early pregnancy to 0.53 ± 0.23. In Sandhoff hétérozygotes the DEAE chromatograms appear normal with higher than normal A/B ratios but in sera, from both pregnant and nonpregnant carriers, the HEX B and HEX I forms are 50% heat labile. During pregnancy, serum can be used as a reliable source of HEX for heterozygote identification for both Sandhoff's and Tay-Sachs disease. © 1979.