Clinical and event-based outcomes of patients with mucopolysaccharidosis VI receiving enzyme replacement therapy in Turkey: a case series

Orphanet J Rare Dis. 2021 Oct 19;16(1):438. doi: 10.1186/s13023-021-02060-4.

PMID: 34666789

Aslı İnci, İlyas Okur, Leyla Tümer

Highlights: This case series shows the high disease burden of the mucopolysaccharidosis (MPS) VI population in Turkey and provides a unique insight into their clinical journey based on real-life clinical and event-based data collected before and after initiation of enzyme replacement therapy (ERT).

Abstract

Background: The goal of this study was to characterize the clinical signs and events of mucopolysaccharidosis (MPS) VI patients treated with galsulfase enzyme replacement therapy (ERT) in Turkey. Clinical data from the medical records of 14 children with MPS VI who were followed up at the Department of Pediatrics at the Gazi University Faculty of Medicine in Ankara, Turkey, were obtained retrospectively. Patients were chosen based on the availability of pre-ERT baseline and follow-up clinical data for a comparable time span (1.9-3.2 years). Data acquired during hospital visits and telemedicine (incidence of acute clinical events, commencement of chronic events, operations) was available for up to 10 years following the start of ERT (2.5-10 years).

Results: The age at which ERT was started ranged from 2.8 to 15.8 years (mean age 7.5 years). On radiography, all of the patients had decreased endurance and skeletal anomalies (dysostosis multiplex). Cardiac valve disease (N = 13), short stature (N = 11), cranial abnormalities on MRI (N = 10), spinal abnormalities on MRI (N = 7) and mild cognitive impairment (N = 6) were also prevalent clinical symptoms. Several patients experienced urine incontinence, and school attendance was frequently poor. Most patients improved their endurance in the 6-minute walk test and 3-minute stair climb tests after 1.9 to 3.2 years of ERT, and urinary incontinence decreased. Cardiac valve disease, eye diseases, hearing loss, and bone disease did not appear to be prevented by ERT. Before starting ERT, long-term event-based data revealed a significant prevalence of respiratory tract infections, adenotonsillectomy/adenoidectomy, poor sleep quality, sleep apnea, and depression. Over the course of 2.5-10 years of follow-up, the number of events in all patients tended to remain stable or decline. However, the character of the occurrences changed over time, with an increase in ophthalmologic events, ear tube insertions, and depression replacing a decrease in respiratory tract infections and sleep issues.

Conclusions: This case series demonstrates the substantial disease burden of the MPS VI community in Turkey and offers a unique perspective on their clinical path based on real-life clinical and event-based data collected before and after ERT beginning.

Keywords: Case series, Enzyme replacement therapy, Galsulfase, Mucopolysaccharidosis VI