Bonnen et al., in AJHG 2013 (93), 471-481 reported a new gene associated with an autosomal recessive disorder of mtDNA depeletion. This gene, FBLX4 was found through whole exome sequencing in a consanguinious family with multiple affected individuals. Gai et al., also published an association of this gene with mitochondrial disease in the same edition of AJHG. FBXL4 is a gene in the F-box domain family, in which other members are associated with substrate adaptors in ubiquitin ligases, among other functions. While both groups conclusively show that the protein product of this gene localizes to the mitochondria, and that there is an associated oxidative phosphorylation defect, neither group determined the mechanistic function within the mitochondria. This leaves the door open for some very interesting disoveries in as of yet undiscovered mitochondrial functions.
Hilary Vernon, MD PhD