Subclinical Respiratory Muscle Weakness and Obstructive Sleep Apnea are Common in Glucosamine-UDP-N-acetyl-2-epimerase / N-acetylmannosamine kinase (GNE) Myopathy.

Glucosamine-UDP-N-acetyl-2-epimerase / N-acetylmannosamine kinase (GNE) myopathy is a rare, slowly progressive myopathy primarily affecting distal muscles. Limited evidence suggests possible respiratory muscle weakness and obstructive sleep apnea (OSA). We aimed to assess daytime lung functions and OSA in GNE myopathy. Nine patients were evaluated by spirometry, maximal inspiratory pressure (MIP), maximal expiratory pressure, single-breath count (SBC), peak cough flow (PCF), arterial blood gases (ABG), sleep questionnaires, and polysomnography. All patients had normal spirometry and ABGs, but 55.6% had decreased MIP, 44.4% had decreased PCF, and 55.6% had SBC<20. Poor sleep quality was common (77.8%). OSA was present in 66.7% of the patients. In conclusion, subclinical respiratory muscle weakness and OSA were frequent in GNE myopathy patients with normal spirometry. Therefore, MIP, PCF, SBC, and polysomnography should be included in routine evaluation.