The functional activity of lysosomal enzymes sialidase, β-galactosidase and N-acetylaminogalacto-6-sulfate-sulfatase in the cell depends on their association in a multienzyme complex with cathepsin A. Mutations in any of the components of this complex result in functional deficiency thereby causing severe lysosomal storage disorders.
Genetic lesions in PPCA lead to a deficiency of beta-galactosidase and neuraminidase that is manifest as the autosomal recessive lysosomal storage disorder galactosialidosis.