Long-term Natural History and Elosulfase Alfa Treatment for Mucopolysaccharidosis Type IVA: A Single-Center Study in the Czech Republic.

Background: Mucopolysaccharidosis type IVA (MPS IVA, Morquio A syndrome) is a rare lysosomal storage disease primarily characterized by severe skeletal dysplasia. Clinical and laboratory data, including treatment responses, are reported for a cohort of Czech patients with MPS IVA. Results: Nineteen patients with MPS IVA from 17 families (13M/6F) were included; only one patient exhibited a mild form. The median age at disease onset was 3.0 ± 1.4 years, whereas the median age at confirmed diagnosis was 5.0 ± 3.5 years. At the time of diagnosis, all patients had skeletal symptoms (pectus carinatum in 58%, short stature in 47%, hip dysplasia in 47%), and 63% had nonskeletal symptoms. Each patient underwent at least one surgical procedure (77% knee, 59% spine, 41% adenotomy). On spinal MRI, 76% of patients presented with cervical stenosis, and 41% presented with cervical myelopathy. Eight patients received ERT for a median duration of 5.5 ± 2.6 years. Compared with non-ERT patients from natural history studies and non-ERT patients within our cohort, beneficial effects were evident in monitored parameters such as changes in the mean FVC and FEV1 volumes and the mean 6MWT distance. Additionally, the hidradenitis suppurativa observed in three patients improved with biologic therapy. We also describe two novel mutations (c.421_422dupTG, c.482G>C). Conclusions: Documenting the natural history of MPS IVA in this population may aid in early diagnosis. Despite the disease's progressive nature, ERT was effective in our MPS IVA patients, demonstrating a consistent impact on endurance across all age groups.