This gene encodes a myotubularin-related protein. The encoded protein is a phosphoinositide phosphatase that specifically dephosphorylates phosphatidylinositol 3,5-biphosphate and phosphatidylinositol 3-phosphate. Mutations in this gene are correlated with autosomal dominant centronuclear myopathy. Alternate splicing results in multiple transcript variants. A pseudogene of this gene is found on chromosome 18.