SUMF1 and Multiple sulfatase deficiency: However, it is also possible that a single mutated gene may result in several impaired hydrolases, as examples we can consider the post-translational deficiencies in Multiple sulphatase deficiency (MSD) formylglycine-generating enzyme (FGE) deficiency (due to Sulfatase Modifying Factor 1 (SUMF1) mutations [95]) and in PSAP, (a precursor polyprotein that requires post-translational cleavage and results in four small activator proteins [98,99]).