Mutations in some phosphoinositide metabolism genes (FIG4, PTEN, MTMR2, and SBF1) also cause neuropathies with conduction slowing and/or CB,26, 27, 28 suggesting a more fundamental role of GPI in the pathophysiology of this inherited neuropathy, independent of the GPI‐APs that are affected. This evidence concerns the gene PTEN and neuropathy.