137 Outcome measures in CMT: case examples from the muscle MRI in CMT study

Background Twelve month increase in muscle fat fraction(FF) at calf has been demonstrated in patients with CMT1A.(1,2) Our MDA funded study builds on our previous work by investigating this method in patients with the three next most common subtypes of CMT: due to mutations in GJ1B, MPZ, and MFN2. Methods Sixty participants and 30 controls have been recruited. In select examples, baseline and follow-up FF were calculated at mid-calf and mid-thigh. Results A 45-year-old male with a MPZ mutation had imaging age 35 (CMTES 17), with FF at calf 20.9%. At age 45, CMTES was 20 and calf FF 35.6%. In a 32-year-old male with GJB1, CMTES rose from 9 to 10 at 12 months, with all muscle mid-calf FF rising from 9.5% to 11.8%. In the left peroneus longus, FF increased from 26% to 55% correlating with reduced ankle plantarflexion power. In a MFN2 patient, baseline CMTES was 16 and at 12-months 17. FF increased at thigh level from 10.5% to 15%. Discussion We present three cases illustrating key points from the study and demonstrate an increase in FF at 12 months in one patient each with CMT1X and CMT2A, and over 10 years in a patient with CMT1B. carolynnedoherty@doctors.org.uk|NIHR Bursary