Sensory ataxic neuropathy with dysarthria and ophthalmoparesis (SANDO) in late life due to compound heterozygous POLG mutations

Missense mutations in the gene for polymerase gamma 1 (POLG1) cause a number of phenotypically heterogeneous mitochondrial diseases, most commonly progressive external ophthalmoplegia, and are characterized by the accumulation of multiple, large-scale deletions of mitochondrial DNA. The triad of sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) has been demonstrated in a small subset of patients with POLG1 mutations. We report a sporadic case of an 80-year-old compound heterozygote man who presented with SANDO and was found to have three known pathogenic mutations in the POLG1 gene (p.T251I/p.P587L/p.G848S). To our knowledge, none of these mutations have been demonstrated previously in SANDO. This patient's late presentation illustrates that a mitochondrial disorder should be considered regardless of age if the clinical symptoms warrant.