Revista de neurologia
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Clinical and biochemical classifications of mitochondrial disorders have given way to an as yet incomplete genetic classification system based on alterations of the mitochondrial genome, the nuclear genome, or both. The first group includes mitochondrial disorders due to specific mutations of mitochondrial DNA such as the MELAS, MERRF or NARP encephalomyopathies, various conditions involving deafness (non-syndromic or associated with diabetes), Leber's optic neuropathy and a small group of cases of maternally transmitted Leigh's syndrome. All these diseases are transmitted through maternal line. conditions which are usually sporadic are due to deletion or duplication of mitochondrial DNA, and give rise to myopathies, with or without ophthalmoplegia, and to more complex disorders such as Kearns Sayre syndrome are also included. ⋯ This includes most cases of Leigh's syndrome, Alpers polydystrophies, the myoneurogastrointestinal syndrome, Barth's syndrome and Friedreich's disease. Amongst the disorders secondary to defects in communication between the nuclear and mitochondrial genomes is a progressive external ophthalmoplegic form with autosomal dominance which arises secondary to mutations on chromosomes 3 and 10. Further mitochondrial disorders due to faults in the relationship between the two genomes will probably be found in the near future.
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The antiepileptic drug gabapentin has begun to be used successfully in some cases of neuropathic pain. Its mechanism of action is still unknown, but seems to be related to a positive effect on the synthesis and liberation of the neurotransmitter GABA. ⋯ Gabapentin should be borne in mind in the treatment of this type of pain, particularly when the usual treatment cannot be given or is insufficient to control pain, especially in elderly patients in whom there is often reduced tolerance of drugs.