This study also concluded that in the presence of POLG-negative ataxia neuropathy spectrum, all patients should be considered for genetic analysis for RNASEH1 mutations since it is the fourth most common cause of adult mendelian PEO with multiple mtDNA deletions in their cohort, following POLG, TWNK and RRM2B [88]. The gene discussed is POLG; the disease is Ataxia.