Multifocal demyelinating motor neuropathy associated with a de novo PTEN mutation

Phosphatase and tensin homolog (PTEN) is a tumour suppressor gene associated with inherited tumour susceptibility conditions, macrocephaly, autism, ataxia, tremor and epilepsy. Functional implications of this protein have been investigated in Parkinson’s and Alzheimer’s diseases. We describe the first patient presented with multifocal demyelinating motor neuropathy in association with a de novo PTEN mutation. The pathogenicity of the mutation was supported by altered expression of several proteins involved in tumorigenesis and fibroblasts showed a reversible defect in catalytic activity of PTEN against the secondary substrate, phosphatidylinositol 3,4,-trisphosphate, suggesting a novel and potentially treatable mechanism for multi-focal demyelinating motor neuropathy.