Beta-Galactosidase Deficiency in the Hurler Syndrome

A deficiency of β-galactosidase (pH 5.0) was found in frozen tissues (brain, liver, kidney and spleen) from 10 patients with Hurler's syndrome (Types 1–3). The diminished activity of this enzyme was demonstrated with the use of nitrophenyl-galactosides as well as ganglioside GM1 and a "keratan sulfate-like" mucopolysaccharide. Mixing experiments demonstrated that soluble endogenous inhibitors are not responsible for the lowered β-galactosidase activity. Activities of related hydrolases, including acid phosphatase, α-glucosidase, β-glucosidase, β-xylosidase, β-N-acetyl-galactosaminidase, β-N-acetyl-glucosaminidase, α-mannosidase, β-glucuronidase and cathepsins A-D, were increased two to five times. Deficiency of β-galactosidase may prove to be the primary enzymic defect in the Hurler syndrome.