MTMR2 and Charcot-Marie-Tooth disease type 4B1: We first demonstrated that loss of function mutations in the MTMR2 (Myotubularin-related 2) gene cause autosomal recessive demyelinating Charcot-Marie-Tooth type 4B1 (CMT4B1, OMIM #601382) neuropathy with myelin outfoldings [8].