Mitochondrial genes, mutations damage

Deoxyribonucleic acid (DNA) has limited chemical stability. As a result, oxidative damage, hydrolysis, and nonenzymatic DNA methylation occur in vivo at significant rates (L6). Thus, another aspect of this theory is that of intrinsic somatic mutations and the ability of cells to repair the damage to both mitochondrial and nuclear DNA. Indeed, mammalian cells have an elaborate system of DNA repair enzymes which become less efficient with time. Thus, failure to repair damaged DNA or to "misrepair it could lead to gene inactivation or possible excision of... 

Symptoms in patients with Wilson s disease usually begin in the second or third decade of life, but may be earlier or later. However, mutations that completely destroy gene function may be associated with onset of liver disease as early as 3 years of age. The initial clinical presentation may be hepatic, with presentation similar to acute hepatitis or to chronic active hepatitis neurological (e.g., clumsiness, dysarthria, ataxia, and tremors) renal (renal tubular acidosis with aminoaciduria) or, less commonly, hematological, with hemolysis secondary to acute release of free copper from tissue and subsequent oxidation of erythrocyte membranes. The hepatic, and possibly CNS, damage may also be secondary to copper-induced oxidative damage to mitochondrial membranes. Hepatic levels of Cp messenger ribonucleic acid (mRNA) are reduced in patients with Wilson s disease, probably secondary to inhibition of transcription by increased intracellular levels of apoCp. ... 

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