Definition:

Alpha-N-acetylgalactosaminidase (NAGA) deficiency is an autosomal recessive lysosomal storage disorder caused by deficiency of alpha-N-acetylgalactosaminidase, which removes terminal alpha-GalNAc monosaccharides from glycolipids and glycoproteins (primarily O-linked). The enzymatic defect results in inappropriate accumulation of substrates in various organ systems. NAGA deficiency is divided into three types. Type 1 is Schindler disease, characterized by mental retardation, spasticity ,and myoclonus. Type 2, known as Kanzaki disease, is an adult-onset disorder characterized by angiokeratoma corporis diffusum and mild intellectual impairment. Type 3 is an intermediate disorder with mild-to-moderate neurologic manifestations.