Diagram showing the disrupted pathway<unk>  is directly caused by a deficiency of the enzyme arylsulfatase A (ARSA) and is characterized by enzyme activity in leukocytes that is less than 10% of normal controls. However, assay of the ARSA enzyme activity alone is not sufficient for diagnosis; ARSA pseudodeficiency, which is characterized by enzyme activity that is 5~20% of normal controls does not cause<unk> . Without this enzyme, sulfatides build up in many tissues of the body, eventually destroying the myelin sheath of the nervous system. The myelin sheath is a fatty covering that protects nerve fibers. Without it, the nerves in the brain (central nervous system – CNS) and the peripheral nerves (peripheral nervous system – PNS) which control, among other things the muscles related to mobility, cease to function properly. Arylsulfatase A is activated by saposin B (Sap B), a non-enzymatic proteinaceous cofactor. When the arylsulfatase A enzyme level is normal but the sulfatides are still high – meaning that they are not being broken down because the enzyme is not activated – the resulting disease is saposin B deficiency, which presents similar to<unk> . Saposin B Deficiency is very rare, much more rare than traditional<unk> . The enzyme that is present is not "enabled" to a normal level of efficiency and can't break down the sulfatides which results in all of the same<unk>  symptoms and progression. A 2011 study contended sulfatide is not completely responsible for<unk>  because it is nontoxic. It has been suggested lysosulfatide, sulfatide which has had its acyl group removed, plays a role because of its cytotoxic properties in vitro.
Metachromatic leukodystrophy
Multiple system atrophy
Leukodystrophy
Benign hereditary chorea
Stratton Parker syndrome
Spinocerebellar ataxia type 6
Infantile neuroaxonal dystrophy
Progressive supranuclear palsy