ASAH1 and glycogen storage disease VI: Types 1, 2, 3, 4, 5, and 6 Farber diseases are associated with the mutations in the ASAH1 gene and the resulting deficiency of AC, whereas type 7 Farber disease is caused by the deficiency of the prosaposin, which is critical for regulating the function of lysosomal enzymes and the development of the neuroprotection [173].