NgaP from GH123 is an excellent tool for detecting sulfatase deficiency, as it does not act on substrates sulfated at positions 4 or 6 of GalNAc32 and has been successfully used for screening of mucopolysaccharidosis (a metabolic disorder caused by the accumulation of mucopolysaccharides) in newborns32,33. The gene discussed is RASAL2; the disease is mucopolysaccharidosis.