Our previous studies made clear the limitations of natural history studies, which involved small sample populations. In order to gain further insight into GNE myopathy for the purpose of improving therapy and care, more patient data are required. To this end, we aimed to develop a nationwide patient registry for GNE myopathy in order to facilitate the planning of clinical trials and recruitment of candidates and to disseminate standard care and current information to patients, physicians, and researchers.

Medical records of genetically confirmed patients with GNE myopathy at the NCNP were retrospectively reviewed in order to obtain data reflecting the severity and progression of the disease. Items selected for the registration sheet included age, sex, age at onset, past history and complications, family history, body weight and height, pathological findings from muscle biopsy, grip power, walking ability, respiratory function, cardiac function, willingness to join upcoming clinical trials, and participation in patient associations. A copy of the original genetic analysis report was required of each patient.

In 2009, we developed a national registry for neuromuscular diseases (Registry of Muscular Dystrophy, Remudy; http://​www.​Remudy.​jp/​, see also Chap. 11) in Japan in collaboration with the TREAT-NMD Alliance in order to aid in the recruitment of eligible patients for clinical trials, provide information regarding the natural history and epidemiology of diseases, and serve as a source of information on current clinical care [13]. Remudy is supported by Intramural Research Grants (23-4/26-7) for Neurological and Psychiatric Disorders from the NCNP. Registry information was provided to interested individuals and their informed consent was obtained. Individuals whose data were included were informed that inclusion in the database confers no obligation to the patient and that they will be removed from the registry immediately upon request. They were also told that refusal to participate would not affect subsequent medical care. Study objectives, design, risks, and benefits of participation were explained to all patients, and their written informed consent was obtained prior to enrollment.

As of the end of October 2013, a total of 121 Japanese patients with GNE myopathy (55 men and 66 women) had registered. Mean ages at data collection and disease onset were 44.9 ± 13.2 years (median, 43 years; range, 21–85 years) and 27.9 ± 9.6 years (median, 26 years; range, 12–61 years), respectively. The registry included patients from throughout Japan (38/47 prefectures) who were recruited through a collaboration with 92 attending physicians from 73 institutes (Fig. 10.2). Three patients had a past history of idiopathic thrombocytopenia (ITP).

Mean age at disease onset was 27.7 ± 9.6 years (median, 27.5 years; interquartile range, 15–61), 20 % (24/121) were ambulant without assistance, 37 % (45/121) required assistance (e.g., canes and/or braces), and 43 % (52/121) had lost ambulation. Mean age at loss of ambulation was 35.4 ± 11.3 years. Kaplan–Meier analysis revealed median durations from disease onset to walking with assistance, wheelchair use, and loss of ambulation of 8.9 years (95 % CI, 6.3–9.7), 14.0 years (95 % CI, 11.8–16.2), and 21.0 years (95 % CI, 15.4–26.6), respectively.