OBJECTIVE: GNE myopathy is a rare autosomal recessive adult-onset distal myopathy caused by biallelic pathogenic variants in GNE. Although some extra-muscular manifestations associated with GNE myopathy have been reported, little is known about whether they are disease-specific and how often they present. This study aimed to characterize extra-muscular manifestations of GNE myopathy. METHODS: We conducted a questionnaire survey of GNE myopathy patients registered in a national registry in Japan. The questionnaire requested information regarding idiopathic thrombocytopenia, cardiac involvement, respiratory involvement, sleep apnea syndrome (SAS), and psychiatric diseases. RESULTS: The response rate was 62.4% (126/198), yielding a total of 51 male and 75 female participants. Of the participants, 4.1% (5/123) had a diagnosis of idiopathic thrombocytopenia, and 16.3% (8/49) of males and 6.6% of females (5/76) had a diagnosis of SAS. In total, 0.8% (1/126) of participants had pervasive developmental disabilities and 14.7% (16/109) had a psychiatric disease. CONCLUSION: The frequencies of idiopathic thrombocytopenia and SAS among Japanese GNE myopathy patients were higher than those observed in the general Japanese population. Routine blood tests and evaluation of sleep-disordered breathing should be considered in order to better manage GNE myopathy patients.