The myotubularin-related genes define a large family of eukaryotic proteins, 
most of them initially characterized by the presence of a ten-amino acid 
consensus sequence related to the active sites of tyrosine phosphatases, 
dual-specificity protein phosphatases and the lipid phosphatase PTEN. 
Myotubularin (hMTM1), the founder member, is mutated in myotubular myopathy, and 
a close homolog (hMTMR2) was recently found mutated in a recessive form of 
Charcot-Marie-Tooth neuropathy. Although myotubularin was thought to be a 
dual-specificity protein phosphatase, recent results indicate that it is 
primarily a lipid phosphatase, acting on phosphatidylinositol 3-monophosphate, 
and might be involved in the regulation of phosphatidylinositol 3-kinase (PI 
3-kinase) pathway and membrane trafficking.