This CPB is revised to state that elosulfase alfa (Vimizim) is considered medically necessary for members with a documented clinical diagnosis of mucopolysaccharidosis type IVA (MPS IVA; Morquio A syndrome) based on clinical signs and symptoms of MPS IVA and documented reduced fibroblast or leukocyte N-acetylgalactosamine-6 sulfatase (GALNS) enzyme activity or genetic testing confirming diagnosis of MPS IVA.