F-box and leucine rich repeat protein 4
The FBXL4 gene provides instructions for making a member of a family of proteins called F-box and leucine rich repeat proteins. Like other members of this family, FBXL4 associates with a group of proteins to form a complex. The protein complex that contains FBXL4 is found within cell structures called mitochondria. Mitochondria are involved in a wide variety of cellular activities, including energy production, chemical signaling, and regulation of cell growth and division (proliferation) and cell death (apoptosis). Mitochondria contain their own DNA, known as mitochondrial DNA (mtDNA), which is essential for the normal function of these structures. As part of the protein complex, the FBXL4 protein is likely involved in the maintenance of mtDNA. Having an adequate amount of mtDNA is essential for normal energy production within cells.
More than 47 mutations in the FBXL4 gene have been found to cause FBXL4-related encephalomyopathic mtDNA depletion syndrome. This condition affects multiple body systems and is often fatal in early childhood. It is primarily associated with brain dysfunction combined with muscle weakness (encephalomyopathy).
Many of the mutations that cause FBXL4-related encephalomyopathic mtDNA depletion syndrome impair the FBXL4 protein's ability to attach (bind) to other proteins, disrupting the formation of the protein complex, which impairs normal maintenance of mtDNA. Problems with mtDNA maintenance can reduce the amount of mtDNA (known as mtDNA depletion). Depletion of mtDNA impairs mitochondrial function in many of the body's cells and tissues. Reduced mitochondrial function eventually leads to cell dysfunction, most noticeably affecting the brain, muscles, and other tissues that have high-energy requirements. This cell dysfunction leads to encephalomyopathy and other features of FBXL4-related encephalomyopathic mtDNA depletion syndrome.
F-box/LRR-repeat protein 4