Mutations in FBXL4 cause mitochondrial encephalopathy and a disorder of mitochondrial DNA maintenance.

TitleMutations in FBXL4 cause mitochondrial encephalopathy and a disorder of mitochondrial DNA maintenance.
Publication TypeJournal Article
Year of Publication2013
AuthorsBonnen, PE, Yarham, JW, Besse, A, Wu, P, Faqeih, EA, Al-Asmari, AMohammad, Saleh, MAM, Eyaid, W, Hadeel, A, He, L, Smith, F, Yau, S, Simcox, EM, Miwa, S, Donti, T, Abu-Amero, KK, Wong, L-J, Craigen, WJ, Graham, BH, Scott, KL, McFarland, R, Taylor, RW
JournalAm J Hum Genet
Date Published2013 Sep 5
KeywordsAcidosis, Lactic, Base Sequence, Child, Child, Preschool, Chromosome Segregation, DNA, Mitochondrial, Electron Transport, F-Box Proteins, Female, Fibroblasts, Gene Dosage, Genes, Recessive, Genetic Predisposition to Disease, Humans, Infant, Infant, Newborn, Male, Mitochondrial Encephalomyopathies, Molecular Sequence Data, Muscle, Skeletal, Mutation, Oxidative Phosphorylation, Pedigree, Protein Transport, Ubiquitin-Protein Ligases

Nuclear genetic disorders causing mitochondrial DNA (mtDNA) depletion are clinically and genetically heterogeneous, and the molecular etiology remains undiagnosed in the majority of cases. Through whole-exome sequencing, we identified recessive nonsense and splicing mutations in FBXL4 segregating in three unrelated consanguineous kindreds in which affected children present with a fatal encephalopathy, lactic acidosis, and severe mtDNA depletion in muscle. We show that FBXL4 is an F-box protein that colocalizes with mitochondria and that loss-of-function and splice mutations in this protein result in a severe respiratory chain deficiency, loss of mitochondrial membrane potential, and a disturbance of the dynamic mitochondrial network and nucleoid distribution in fibroblasts from affected individuals. Expression of the wild-type FBXL4 transcript in cell lines from two subjects fully rescued the levels of mtDNA copy number, leading to a correction of the mitochondrial biochemical deficit. Together our data demonstrate that mutations in FBXL4 are disease causing and establish FBXL4 as a mitochondrial protein with a possible role in maintaining mtDNA integrity and stability.

Alternate JournalAm. J. Hum. Genet.
PubMed ID23993193
PubMed Central IDPMC3769921
Grant List096919 / / Wellcome Trust / United Kingdom
096919/Z/11/Z / / Wellcome Trust / United Kingdom
AI036211 / AI / NIAID NIH HHS / United States
CA125123 / CA / NCI NIH HHS / United States
G0601943 / / Medical Research Council / United Kingdom
MR/K000608/1 / / Medical Research Council / United Kingdom
R01 GM098387 / GM / NIGMS NIH HHS / United States
RR024574 / RR / NCRR NIH HHS / United States