Abstract
There is a growing interest in evaluating the effectiveness of enzyme replacement therapy (ERT) with elosulfase alfa in patients with mucopolysaccharidosis type IVA (MPS-IVA) under real-world conditions. We present the experience of seven pediatric MPS-IVA patients from the Spanish Morquio-A Early Access Program. Efficacy was evaluated based on the distance walked in the 6-min walking test (6-MWT) and the 3-min-stair-climb-test (3-MSCT) at baseline and after 8 months of ERT treatment. Additionally, urinary glycosaminoglycans were measured, and a molecular analysis of a GALNS mutation was performed. The health-related quality of life was evaluated using the EuroQoL (EQ)-5D-5 L.The distance walked according to the 6-MWT ranged from 0 to 325 m at baseline and increased to 12–300 m after 8 months with elosulfase alfa (the walked distance improved in all patients except one). An increase was observed for the two patients who had to use a wheelchair. Improvements were also observed for the 3-MSCT in four patients, whereas two patients showed no changes. Three patients showed an improvement in the EQ-VAS score, whereas the scores of three patients remained stable. Regarding urinary glycosaminoglycans measurements, an irregular response was observed. Our results showed overall improvement in endurance and functionality after 8 months of elosulfase alfa treatment in a heterogeneous subset of MPS IVA patients with severe clinical manifestations managed in a real-world setting.
Highlights
Mucopolysaccharidosis type IVA (MPS IVA; Morquio A syndrome, OMIM 253000) is an autosomal recessive lysosomal storage disorder (LSD) that was first described by Luis Morquio and James Brailsford in 1929 [1]
MPS IVA is caused by a deficiency of the N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme, which leads to a progressive accumulation of the glycosaminoglycans (GAGs) chondroitin-6-sulfate (C6S) and keratan sulfate (KS)
The evolution of endurance was evaluated with the 6-min walking test (6-MWT) and the 3-MSCT, which are represented in Figs. 1 and 2, respectively
Summary
Mucopolysaccharidosis type IVA (MPS IVA; Morquio A syndrome, OMIM 253000) is an autosomal recessive lysosomal storage disorder (LSD) that was first described by Luis Morquio and James Brailsford in 1929 [1]. The accumulation of undegraded C6S and KS triggers progressive systemic skeletal dysplasia in MPS IVA patients [2,3,4,5]. MPS IVA is more frequently associated with severe and extensive skeletal manifestations than the other MPS types. Hypermobility of the joints is a characteristic of MPS IVA that distinguishes this disease from the other types. These patients exhibit no cognitive involvement [9]. Patients with a severe form of MPS IVA may not survive beyond the second or third decade of life
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