Impairment of respiratory function in late-onset distal myopathy due to MATR3 Mutation

Introduction: Recently, mutations in the MATR3 gene were found to cause late-onset distal myopathy. The frequency and impact of respiratory involvement are not clear.

Methods: Respiratory parameters [maximum vital capacity (VCmax); forced expiratory volume (FEV1 ); peak expiratory flow (PEF), postural drop of VCmax from sitting to supine, maximum inspiratory muscle pressure (PImax), mouth occlusion pressure after 100 ms (P 0.1), peak cough flow, and blood-gas analysis] were monitored prospectively at baseline, and then 6 months and 12 months later in 8 patients with genetically confirmed MATR3 myopathy.

Results: All patients showed involvement of respiratory function. Six of 8 reported exertional dyspnea. At the end of follow-up, 5 of 8 had decreased VC, 7 of 8 had reduced PImax, and 5 of 7 had decreased partial pressure of oxygen (PO2 ). Within 12 months, respiratory parameters deteriorated non-significantly. No patient required non-invasive ventilation.

Conclusions: There is a high risk of abnormal respiratory function with progressive worsening in MATR3 myopathy.