Repeated clear benefits of immunotherapy in a patient with Charcot-Marie-Tooth disease carrying a rare point mutation in PMP22.

We describe a unique patient who had been diagnosed with inflammatory demyelinating polyneuropathy (CIDP) for 13 years with frequent clear responses to immunotherapies and was finally diagnosed with Charcot-Marie-Tooth disease (CMT) with a rare point mutation in PMP22 (c.320G > A, p.G107D). Some patients diagnosed with young-onset CIDP may have underlying CMT, and extensive genetic testing including point mutations of PMP22 gene is required not to miss the diagnosis.