After informed consent had been obtained from the patients affected from MONA spectrum disorder the investigators assessed the patients regarding the following characteristics: consanguinity, clinical symptoms at diseases on-set, age at on-set of symptoms and age at diagnosis, cognitive development, progression of clinical symptoms related to the diagnosis, molecular investigations, associated disorders as well as therapies besides bisphosphonate therapy. Informed consent from the patients was also obtained to publish the patient's photographs. All investigations are performed according to the relevant ethical guidelines.