A Japanese case of cerebellar ataxia, spastic paraparesis and deep sensory impairment associated with a novel homozygous TTC19 mutation

Mitochondrial complex iii (ciii) deficiency comprises a group of complex and heterogeneous genetic disorders. ttc19 mutations constitute a rare cause of ciii deficiency and are associated with neurological disorders in childhood and adulthood. herein, we describe a 27-year-old japanese man with cerebellar ataxia, spastic paraparesis, loss of deep sensation, mild frontal lobe dysfunction and transient psychiatric symptoms. brain magnetic resonance imaging showed cerebellar atrophy and bilateral high-intensity signals in the inferior olives and regions adjacent to periaqueductal gray matter, on t2-weighted images. on whole-exome sequencing, we detected a novel homozygous frameshift mutation c.157_158dup [p.pro54alafs*48] in ttc19. mitochondrial enzyme assays confirmed mild impairment of ciii enzymatic activity in lymphoblasts, which was consistent with ttc19-related ciii deficiency. his symptoms and radiological findings demonstrated an early stage or mild form of this disease, and further clarify the characteristics of patients with rare ttc19 mutations.