TTC19-related mitochondrial disease: A characteristic neuroimaging signature?
BACKGROUND TTC19-related mitochondrial disease is a rare mitochondrial disorder of respiratory chain Complex III (CIII), typically associated with neurodegeneration and Leigh syndrome. However, its clinical presentation is variable, which complicates diagnosis and management. OBJECTIVE To characterize the clinical and neuroimaging features of pediatric patients with TTC19 variants, focusing on disease course and outcomes. METHODS We conducted a multicentric retrospective study of 11 patients diagnosed with TTC19 variants in France. Data were collected from patients'medical records from multiple mitochondrial disease reference centers, encompassing demographic, clinical, neuroimaging, and genetic information. Brain MRIs were reviewed by a sole neuroradiologist expert to standardize findings. All patients had genetic confirmation of TTC19-related mitochondrial disease. RESULTS The cohort consisted of 6 families, with a mean age at onset of 5.7 years (range: 0.8-15 years). Patients exhibited two distinct clinical patterns: progressive neurodegenerative disease (chronic Leigh syndrome) and acute/subacute Leigh syndrome. Neuroimaging consistently revealed striatal lesions in all patients and brainstem involvement in almost all of them. Additional findings included cerebellar atrophy and lactate peak on MR spectroscopy. Clinical manifestations were predominantly neurological, with motor involvement including, dystonia, cerebellar ataxia, and orofacial apraxia and frequently cognitive impairments. Acute Leigh episodes were observed in many patients, leading to sudden deterioration. The disease progression varied, with patients experiencing progressive decline, stepwise declines and others remaining stable between episodes. CONCLUSION TTC19-related mitochondrial disease leads to a severe neurodegenerative phenotype, characterized by early-onset motor and cognitive delays, with a consistent neuroimaging signature involving the striatum and brainstem. This study expands the understanding of TTC19-related mitochondrial disease and underscores the importance of neuroimaging in diagnosis and management.