Abstract

Isolated biochemical deficiency of mitochondrial complex I is the most frequent signature amongst mitochondrial diseases and is associated with a wide variety of clinical symptoms. Leigh syndrome represents the most frequent neuroradiological finding in patients with complex I defect and >80 monogenic causes have been involved in the disease. In this report, we describe 7 patients from four unrelated families harbouring novel NDUFA12 variants, 6 of them presenting with Leigh syndrome. Molecular genetic characterization was performed using next generation sequencing combined with the Sanger method. Biochemical and protein studies were achieved by enzymatic activities, blue native gel electrophoresis and Western blotting. All patients displayed novel homozygous mutations in the NDUFA12 gene leading to the virtual absence of the corresponding protein. Surprisingly, despite in none of the analyzed patients NDUFA12 protein was detected, they present a different onset and clinical course of the disease. Our report expands the array of genetic alterations in NDUFA12 and underlines phenotype variability associated with NDUFA12 defect. This article is protected by copyright. All rights reserved.