P84-F Subacute polyneuropathy partially responsive to immunomodulatory treatment coexisting with POLG mutation

Background During the last few years, the correlation between mitochondrial disorders and autoimmune diseases has been reported. Autoimmune polyneuropathies were concomitant with symptoms related to the polymerase γ (POLG) mutations. POLG is involved in mitochondrial DNA (mtDNA) replication and maintenance. Material and methods We present a case of a16-year-old girl with W748S mutation of POLG region with a 1,5-year history of slowly progressive walking difficulties. Results In the neurological examination the girl had ataxic gait with sensory disturbances in lower extremities with areflexia. Nerve conduction studies (NCS) demonstrated axonal–demyelinating sensorimotor polyneuropathy of the lower limbs. Additionally, magnetic resonance imaging (MRI) of the lumbar spine revealed gadolinium enhancement of the spinal roots and an examination of cerebrospinal fluid showed dissemination. The immunomodulatory treatment with intravenous methylprednisolone and intravenous immunoglobulin (IVIg) was started. Conclusions The IVIg and IVMP treatment led to marked improvement of her abnormal gait and improved resolution of abnormalities of touch, temperature sensation and improved proprioception. The W748S mutations were commonly reported and associated with variable phenotypes, most often Alpers syndrome, but also polyneuropathy. However, electrodiagnostic features and partial response to immunomodulatory therapy suggest the autoimmune etiology of the patients’ subacute symptoms. We hypothesize that oxidative stress caused by impaired mitochondria function may trigger an autoimmune response.