Dorsal root ganglionopathy as the initial presenting feature in POLG-related Mitochondrial disease

<h3></h3> Pathogenic variants in <i>POLG,</i> encoding for the catalytic subunit of mitochondrial polymerase gamma, can present with either severe early onset myocerebrohepatopathy spectrum disorder (MCHS) and Alpers-Huttenlocher Syndrome (AHS), or late-onset presentations, which commonly include progressive external ophthalmoplegia, peripheral neuropathy and cerebellar ataxia. Although axonal neuropathy is frequently documented in <i>POLG</i> disease, the contribution of dorsal root ganglionopathy to the ataxic symptoms and overall disease burden in patients remains poorly recognised. Here we report on a case series comprising two female and two male patients with recessive <i>POLG-</i>related mitochondrial disease, who presented with progressive balance impairment and a clinical diagnosis of dorsal root ganglionopathy as the first symptom, ranging from late teens to sixties. The average time to reach a diagnosis from the onset of sensory symptoms was 4.7 years. The diagnostic pitfalls, the importance of neurophysiology, and the evolution and pattern of progression of the disease will be highlighted. Given the carrier frequency of common <i>POLG</i> variants is estimated at 1-2% of Northern and Western European populations, POLG disease should be considered early in the differential diagnosis for patients manifesting with sensory ataxia and dorsal root ganglionopathy.