Re: what genes are contained in the mitrochondria and what diseases can arise

The mitochondrial genome (mtDNA) in humans is contained on a single circular chromosome 16,569 basepairs around, and each mitochondrion contains 5 to 10 copies of the mitochondrial chromosome. There are several essential genes in mtDNA that are involved in replication and translation, along with some genes that are crucial for the machinery that converts metabolic energy into ATP. These include NADH dehydrogenase, cytochrome c oxidase, ubiquinol/cytochrome c oxidoreductase, and ATP synthase, as well as the genes for unique Ribosomal RNA and Transfer RNA particles which are required for translating these genes into proteins.

There are specific diseases associated with mutations in some of these genes. Below are the most commonly affected genes and the diseases arising from their mutation.

NADH dehydrogenase:

Severe progressive tubulointerstitial nephritis, a kidney disease that can lead to renal failure, has shown the presence of distorted mitochondria, resulting from a point mutation in ND2 gene. Leber's hereditary optic neuropathy, LHON, arises from mitochondrial DNA mutations in the ND1 and ND4 genes (and in some cases the ubiquinol gene). Eight of these mutations frequently associated with LHON, have also been found in patients with Multiple Sclerosis.

ATP synthase:

Myoclonic Epilepsy and Ragged Red Fiber disease, MERRF, involves mutation of the ATPase 8 gene. While Neurogenic muscle weakness, Ataxia, and Retinitis Pigmentosum, NARP, results from mutations in the ATPase 6 gene.

Transfer RNA genes:

Mitochondrial Encephalomyopathy, Lactic Acidosis, and Strokelike symptoms, MELAS, and Maternally inherited Myopathy and Cardiomyopathy MMC, are caused by different mutation in the gene for the tRNA responsible for adding the amino acid Leucine to mitochondrial proteins.

Large deletions:

Pearson's marrow/pancreas syndrome is one of a few disease associated with a large deletion in the mtDNA. The various tissues of each patient contain populations of both wild-type and deleted mtDNA molecules, suggesting that this disease arises from ongoing damage to the mtDNA, rather than an inherited mutation. Because of the varied population, the clinical expression of Pearson's syndrome is variable and is not correlated with the size and position of the mtDNA deletion.

Molecular Biology of the Cell by Bruce Alberts, et al. - 3rd ed., Garland Publishing, Inc., New York & London, 1995.

An Introduction to Genetic Analysis by Anthony J.F. Griffiths, et al. - 5th ed., W.H. Freeman and Company, New York, 1993.

or search this site for "Mitochondria".