Morquio B patient/caregiver survey: First insight into the natural course of a rare GLB1 related condition.

Morquio B disease (MBD) or Mucopolysaccharidosis type IV B (MPS IV B) is caused by particular GLB1 mutations specifically affecting the affinity of beta-galactosidase to keratan sulphate, resulting in dysostosis multiplex resembling Morquio A (MPS IV A) disease (GALNS deficiency). Additional neuronopathic features of GM1 II/III (juvenile/adult) gangliosidosis have been reported in some patients. Our patient/caregiver online survey was aimed at elucidating the clinical manifestations of this ultra-rare condition.