The youngest pair of siblings with Mucopolysaccharidosis type IVA to receive enzyme replacement therapy to date: A case report.

Mucopolysaccharidosis type IVA (OMIM 253000) is an autosomal recessive disorder caused by defective activity of the N-acetylgalactosamine 6-sulfatase (GALNS) enzyme. In 2014, enzyme replacement therapy (ERT) using recombinant human GALNS became available for affected patients. There is a limited number of studies to date that have explored the effect of ERT in infancy and there is also a lack of data assessing the effect of ERT in systems other than the skeletal.