[Current and future aspects of mitochondrial diseases].
Though mitochondria have been a major source of energy production in eukaryotae since 15-20 billion years previously, existence of disorders due to primary abnormalities of their DNA has not been known until very recent years. In 1962, Luft et al reported the first case of such myopathy, and another case reported in 1967 by Shy et al was also the first case of generalized disorder with mitochondrial abnormalities. Since then, many case reports have followed including MELAS and other encephalomyopathies. Finally, in 1989, deletion of mitochondria DNA was found by Folt et al. Today, these disorders were able to be classified as follows: 1) LHON and A1555G type deafness as strictly limited non-syndromic type, 2) encephalomyopathies and their incomplete forms due to common and other deletions of mitochondria DNA, 3) encephalomyopathies and their incomplete forms including MIDD, diabetes mellituis, cardiomyopathy, deafness due to point mutations of mitochondria DNA related MELAS and others, 4) Neurodegenerative types including Parkinson's disease, Alzheimer's disease, cerebellar degeneration, and amyotrophic lateral sclerosis, or neurologic disorders mimic to such diseases, 5) Mitochondrial involvement not due to primary abnormalities of mitochondria DNA. Possible mechanisms were discussed, but sufficient knowledge is lacking so far to clarify pathophysiology of these disorders and the role of deleterious DNA in aging. Possible effective therapeutic strategies were also discussed, but further development of research works on these disorders in the 21st century are needed to answer these questions.