CMT4B1 (MIM 601382) is caused by mutations in the myotubularin family member MTMR2 (Bolino et al., 2000), whereas CMT4B2 (MIM 604563), which can also feature glaucoma, is caused by mutations in MTMR13 (SBF2) (Senderek et al., 2003), which encodes a phosphatase-dead myotubularin-related protein that interacts directly with MTMR2 (Robinson and Dixon, 2005). This evidence concerns the gene SBF2 and glaucoma.