LHON: Mitochondrial Mutations and More

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Mitochondria are small organelles found in eukaryotic cells which respire aerobically. They are responsible for generating energy from food to ‘power the cell’. They contain their own DNA, reproducing by dividing in 2. As they closely resemble bacteria, it gave the idea that they were derived from bacteria (which were engulfed by ancestors of the eukaryotes we know today). This idea has since been confirmed from further investigations, and it is now widely accepted. (Alberts et al., 2010a) The genes which encode for the mitochondria’s component proteins are in 2 separate genetic systems in 2 different locations. One of which is the cell nucleus, but the other is inside the organelle itself. There are relatively few genes inside the organelle, as most of the bacterial genes have been transposed to the cell nucleus. 16569 nucleotide pairs of DNA make up the human mitochondrial DNA, encoding 37 genes. (Alberts et al., 2010b). Both mitochondria and their DNA are inherited almost entirely from the mother. Mitochondrial DNA is more at risk from spontaneous mutation than DNA found in the cell nucleus. Some somatic effects associated with aging are potentially due to the accumulation of mutations in mitochondrial DNA. (Turnpenny and Ellard, 2012) Mitochondria are essential in the cellular generation of ATP. This is because the genome encodes for 13 proteins, 2 ribosomal genes, and 22 tRNAs which are essential for this process in eukaryotic cells. Many maternally inherited diseases are due to germline mutations in mitochondrial DNA (mtDNA). But somatic mtDNA mutations may have great effects on aging and cancer. (Hartmann A, 2008) Leber hereditary optic neuropathy (LHON) is caused by mtDNA mutations and is a maternally inherited disorder... ... middle of paper ..., 48, 935-942. 9) Huoponen K, VilkkiJ, Aula P, Nikoskelainen E, Savontaus M (1991) Am. J. Hum. Genet, 48, 1147-1153. 10) Brown MD. (1999) The enigmatic relationship between mitochondrial dysfunction and Leber's hereditary optic neuropathy. J Neurol Sci. 165:1–5 11) Hudson G, Yu-Wai-Man P, Chinnery P F (2008) Leber hereditary optic neuropathy. Expert opinion on Medical Diagnostics. Vol 2, No. 7 p789-799. 12) Man, P. Y., et al. (2003) The epidemiology of Leber hereditary optic neuropathy in the North East of England. American Journal of Human Genetics 72, 333-339 13) Chial, H. & Craig, J. (2008) mtDNA and mitochondrial diseases. Nature Education 14) Man P Y W, Turnbull D M, Chinnery P F (2002) Leber hereditary optic neuropathy. J Med Genet 39, 162-169. 15) Taylor R W, Turnbull D M. (2005) Mitochondrial DNA Mutations in Human Disease, Nat Rev Genet. 389-402.
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