SANDO
SANDO / Sensory Ataxia Neuropathy, Dysarthria, Opthalmoplegia - POLG, PEO1/Twinkle
Clinical Features
SANDO is a clinically heterogeneous systemic disorder with variable features resulting from mitochondrial dysfunction. It shares phenotypic characteristics with autosomal recessive progressive external ophthalmoplegia and mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE). SANDO is an adult onset disease starting usually between the 16-40 years of age. The typical clinical symptoms are sensory ataxic neuropathy in association with dysarthria and chronic progressive external ophthalmoplegia. Patients usually have ataxic gait, loss of distal proprioception and vibration, areflexia in the lower limbs, positive Romberg sign, and electrophysiological and pathological evidence of a peripheral axonal neuropathy. Other variable features include migraine and depression. Skeletal muscle biopsy usually shows myopathic changes with central nuclei and ragged red fibers. Molecular analysis usually shows multiple mtDNA deletions in muscle and peripheral nerve.
Genetic Information
SANDO is most frequently caused by mutations in the nuclear-encoded polymerase-gamma gene (POLG1). Less frequently mutations in the Twinkle (C10ORF2) gene were also described. Usually multiple mtDNA deletions are detectable in muscle DNA.
Prevalence
No data
Diagnostic
Indication
Method
1. Mutation analysis of the entire coding and flanking intronic regions with intronic primers of the POLG1 gene by direct DNA sequencing
2. Mutation analysis of the entire coding and flanking intronic regions with intronic primers of the Twinkle gene by direct DNA sequencing
Sample Requirement
2 - 4 ml EDTA-blood
Duration
2 - 4 weeks