Sensory ataxic neuropathy with dysarthria and ophthalmoplegia (SANDO) syndrome

Missense mutations in the gene for polymerase gamma 1(POLG1) cause a number of phenotypically heterogeneous mitochondrial diseases. The triad of sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) has been demonstrated in a small subset of patients with POLG1 mutations. 34 years old gentleman presented with severe sensory ataxic neuropathy in association with dysarthria, dysphagia and chronic progressive external ophthalmoplegia. Electrophysiological studies showed features of severe axonal loss disproportionately affecting sensory nerves. Needle EMG showed mixed myopathic and neurogenic pattern. Muscle biopsy showed absence of cytochrome oxidase (COX) activity with COX and COX with succinate dehydorgenase (SDH) staining in some muscle fibres, however there was no features of ragged red fibres on modified Gomoris trichrome staining. Muscle biopsy features were suggestive of mitochondrial cytopathy with associated Myopathy. Molecular genetic analysis revealed heterozygous mutations, c.2243GC and c.911TG. at exon 13 and exon 4 respectively.Sensory ataxic neuropathy may be the predominant and presenting manifestation of a mitochondrial disorder, and the triad of sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) may represent a novel mitochondrial disease associated with POLG 1 mitochondrial mutation. So possibility of a mitochondrial disorder should be considered with this phenotypic presentation, positive family history and then do appropriate investigations including muscle biopsy and genetic testing to confirm the diagnosis