In this study we describe two unrelated male patients with late-onset, predominantly motor, axonal neuropathy with neuromyotonia, who carried an autosomal dominant c.103G > A mutation in the myelin protein zero (MPZ) gene (NM_000530.8:c.103G > A, p.Asp35Asn), identified by whole-exome sequence analysis (WES). The gene discussed is MPZ; the disease is Isaacs syndrome.