Long-term follow-up and response to elosulfase alfa in mucopolysaccharidosis type IVA: a single-center cohort from 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 (13 M/6F) were included; only one patient exhibited a mild form. The median age at first symptom onset was 3.0 years (IQR 1.6-3.4), whereas the median age at confirmed diagnosis was 5.0 years (IQR 3.9-5.7). 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 magnetic resonance imaging, 76% of patients presented with cervical stenosis, and 41% had cervical myelopathy. Eight patients received enzyme replacement therapy for a median duration of 5.5 years (IQR 4.2-6.4). Stabilization or improvement in monitored parameters, including mean forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and mean 6-Minute Walk Test distance, were observed in treated patients. Additionally, the hidradenitis suppurativa observed in three patients improved with biologic therapy. We also describe two novel variants (c.421_422dupTG, c.482G > C). CONCLUSIONS: Documenting the natural history of MPS IVA in this population may aid early diagnosis. Despite the disease's progressive nature, ERT led to stabilization of monitored parameters in treated children.