IMPACT OF THE 25TH CHROMOSOME ON MITOCHONDRIAL DYSFUNCTION IN HUMAN-DISEASE

Human mitochondrial DNA, the 25th chromosome, is a 16 569 base pair lo ng, closed circular molecule, that encodes a variety of genes for the translational machinery of the mitochondrion, as well as 13 structural proteins, that are all subunits of the respiratory chain (RC). A vari ety of alterations of mitochondrial DNA (mtDNA) are now functionally a nd genetically linked to human disease, including encephalomyopathies, Leber's hereditary optic neuropathy, diabetes mellitus, some neurogen erative diseases and even ageing. The mitochondrial encephalomyopathie s are a clinically, biochemically and genetically heterogeneous group of disorders. Alterations of mtDNA include point mutations, deletions, duplications and copy-number mutations. The pathogenetic mechanisms o f mtDNA defects in mitochondrial encephalomyopathies, as well as in th e other human diseases, are reviewed.