Mutation screening of 75 candidate genes in 152 complex I deficiency cases identifies pathogenic variants in 16 genes including NDUFB9. Issue 2 (26th December 2011)

• Record Type: Journal Article
• Authors: Haack, Tobias B; Madignier, Florence; Herzer, Martina; Lamantea, Eleonora; Danhauser, Katharina; Invernizzi, Federica; Koch, Johannes; Freitag, Martin; Drost, Rene; Hillier, Ingo; Haberberger, Birgit; Mayr, Johannes A; Ahting, Uwe; Tiranti, Valeria; Rötig, Agnes; Iuso, Arcangela; Horvath, Rita; Tesarova, Marketa; Baric, Ivo; Uziel, Graziella; Rolinski, Boris; Sperl, Wolfgang; Meitinger, Thomas; Zeviani, Massimo; Freisinger, Peter; Prokisch, Holger
• Is Part Of: Journal of medical genetics. Volume 49:Issue 2(2012)
• Page Start: 83
• Page End: 89
• Publication Date: 2011-12-26
• Subjects: Mitochondrial complex I deficiency -- high resolution melting curve analysis -- lentiviral complementation -- NDUFB9 -- genetic screening/counselling -- molecular genetics -- metabolic disorders -- genetics -- Complex I, neurology -- neurosciences -- neurology -- neuromuscular disease -- muscle disease -- clinical genetics -- endocrinology; Medical genetics -- Periodicals; 616.042
• DOI: 10.1136/jmedgenet-2011-100577
• Languages: English
• ISSNs: 1468-6244

Abstract

Abstract : Background: Mitochondrial complex I deficiency is the most common cause of mitochondrial disease in childhood. Identification of the molecular basis is difficult given the clinical and genetic heterogeneity. Most patients lack a molecular definition in routine diagnostics. Methods: A large-scale mutation screen of 75 candidate genes in 152 patients with complex I deficiency was performed by high-resolution melting curve analysis and Sanger sequencing. The causal role of a new disease allele was confirmed by functional complementation assays. The clinical phenotype of patients carrying mutations was documented using a standardised questionnaire. Results: Causative mutations were detected in 16 genes, 15 of which had previously been associated with complex I deficiency: three mitochondrial DNA genes encoding complex I subunits, two mitochondrial tRNA genes and nuclear DNA genes encoding six complex I subunits and four assembly factors. For the first time, a causal mutation is described in NDUFB9, coding for a complex I subunit, resulting in reduction in NDUFB9 protein and both amount and activity of complex I. These features were rescued by expression of wild-type NDUFB9 in patient-derived fibroblasts. Conclusion: Mutant NDUFB9 is a new cause of complex I deficiency. A molecular diagnosis related to complex I deficiency was established in 18% of patients. However, most patients are likely to carry mutations in genes so far not associated with complex I function. The authors conclude that the high degree of genetic heterogeneity in complex I disorders warrants the implementation of unbiased genome-wide strategies for the complete molecular dissection of mitochondrial complex I deficiency.