Clinical spectrum and frequency of Charcot-Marie-Tooth disease in Italy: data from the national CMT registry

Background: We report data from the Italian CMT Registry. Methods: The Italian CMT Registry is a dual registry where the patient registers, chooses a reference centre, where the attending clinician collects a minimal dataset of information and administers the CMT Examination/Neuropathy Score. Entered data are encrypted. Results: Overall, 1012 patients had registered (535 females) and 711 had received a genetic diagnosis. Demyelinating CMT (65.3%) was more common than axonal CMT2 (24.6%) and intermediate CMT (9.0%). The PMP22 duplication was the most frequent mutation (45.2%), followed by variants in GJB1 and MPZ (both ~10%) and MFN2 (3.3%) genes. We observed a relatively high mutation rate in some "rare" genes (HSPB1 1.6%, NEFL 1.5%, SH3TC2 1.5%) and the presence of multiple mutation clusters across Italy. CMT4A was the most disabling type, followed by CMT4C and CMT1E. Disease progression rate differed, depending on the CMT subtype. Foot deformities and walking difficulties were the main features. Shoe inserts and orthotic aids were used by almost one half of all patients. Scoliosis was present in 20% of patients, especially in CMT4C. Recessive forms had more frequently walking delay, walking support need and wheelchair use. Hip dysplasia occurred in early-onset CMT. Conclusions: The Italian CMT Registry has proven to be a powerful data source to collect information about epidemiology and genetic distribution, clinical features and disease progression of CMT in Italy and is a useful tool for recruiting patients in forthcoming clinical trials.