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The article focuses on the Alpha-synuclein pathology and Parkinsonism associated with POLG1 mutations and multiple mitochondrial DNA deletions. It states that the dorsal nucleus of vagus and the other brainstem and subcortical nuclei showed only mild LB pathology. The authors speculated that high levels of mtDNA deletions present in that patient may have caused premature ageing and the earlier onset of AD, which usually occurs at a more advanced age.

Mitochondrial abnormalities, in particular the accumulation of mitochondrial DNA mutations, have been proposed as a potential cause of normal ageing. One group of patients with mtDNA disorders have a nuclear DNA defect which accelerates the chronological accumulation of mitochondrial DNA mutations. These patients provide an ideal means of investigating whether accelerated mitochondrial DNA defects can cause accelerated ageing pathology. The choroid plexus demonstrates a robust accumulation of pathological changes, in the form of Biondi bodies, with normal ageing. We have therefore examined the choroid plexus of a case with multiple mitochondrial DNA deletions for evidence of accelerated ageing and compared it with two cases with point mutation mitochondrial DNA disorders and several age-matched and elderly controls with and without clinical and neuropathological evidence of neurodegenerative disease. We also demonstrate that the choroid plexus of the mitochondrial DNA cases contain cells with levels of mitochondrial DNA mutation sufficient to cause a biochemical deficiency in the oxidative phosphorylation pathway. As previously reported, both cases with point mutation mitochondrial DNA disorders exhibit a characteristic oncocytic type transformation of the choroidal epithelial cells. However, in the case with multiple mitochondrial DNA deletions we demonstrate pathological changes in choroid plexus that are strongly suggestive of accelerated ageing. We believe that this finding supports the theory that the accumulation of mitochondrial DNA mutations can lead to pathological changes typical of ageing cells. [ABSTRACT FROM AUTHOR]

Focuses on a study which determined whether recombination has contributed to the distribution of human mitochondrial genome (mtDNA) polymorphisms in humans. Nucleotide sequences of mtDNA in the European population; Analysis of mtDNA linkage disequilibrium as a function of distance; Excess homoplasy test for recombination.

Mitochondrial DNA (mtDNA) is the only autonomously replicating source of DNA outside the nucleus. The mitochondrial genome encodes thirteen essential polypeptides of the mitochondrial respiratory chain. Defects of the mitochondrial genome can cause severe neurological and multi-systemic disorders. In many patients there is a mixture of mutated and wild-type mtDNA in the same cell (a situation termed heteroplasmy). In these patients the ratio of mutated to wild-type mtDNA is crucial and a biochemical defect only occurs with relatively high levels of mutated mtDNA within an individual cell. This threshold also seems to be critical in the development of mtDNA disease. Since the genetic defect causes a dysfunction in the terminal stage of oxidative metabolism, there is little potential for pharmacological intervention. Molecular techniques must be developed to reverse the ratio of mutated and wild-type mtDNA. In this paper we summarise our approach using both antigenomic peptide nucleic acids and cell necrosis. [ABSTRACT FROM AUTHOR]

This article focuses on a study that finds no association of the mitochondrial DNA A 12308G polymorphism with increased risk of stroke in patients with the A3242G mutation. Only 50% of patients carrying the A3243G mutation have stroke-like episodes and the reason for this clinical variability remains poorly understood. It is responsible for 80% of cases of MELAS, mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes, and is also associated with several other phenotypes including maternally inherited diabetes and deafness and chronic progressive external ophthalmoplegia. Researchers carried out a large, multicentre study to investigate the A12308G polymorphism in a group of 107 unrelated family index cases harbouring the A3243G mutation.

The article describes a case where an asymptomatic 29-year-old woman carrying a known mutation of mitochondrial DNA developed pre-eclampsia complicated by magnesium toxicity at therapeutic plasma level. The patient presented at 38+5 weeks' gestation with ruptured membranes, raised blood pressure and proteinuria, with pathologically brisk reflexes and mild biochemical derangement. She was given magnesium sulphate and labetalol prior to prostaglandin and oxytocin induction.

Defects of mitochondrial function have been proposed as a potential mechanism in the development and pathogenesis of Alzheimer's disease (AD) and neuronal apoptosis. Mitochondrial enzyme-deficient pyramidal neurones are found in greater quantities in the hippocampus of AD patients than in age-matched controls. The presence of these neurones indicates that high levels of mutant mtDNA (mitochondrial DNA), sufficient to cause a biochemical deficiency within individual neurones, occur more frequently in AD than in normal ageing. This study analyses the relationship of cytochrome c oxidase (COX)-deficient neurones with the neuropathological markers of AD, neurofibrillary tangles (NFTs) and amyloid plaques, as well as markers of neuronal apoptosis known to occur in AD brains. Frozen sections of hippocampi from three AD patients were used to directly colocalize in situ the presence of histochemically COX-deficient neurones with immunohistology for the classical neuropathological markers of AD, tau and β-amyloid. In addition, we also directly colocalized these mitochondrial-enzyme deficient neurones using terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling and cleaved caspase-3. The distribution of amyloid plaques is anatomically distinct from the COX-deficient hippocampal pyramidal neurones and the neurones that contained NFTs or apoptotic labelling were always COX-positive. COX-deficient, succinate dehydrogenase-positive hippocampal neurones indicative of high mtDNA mutation load do not appear to be prone to apoptosis or to directly participate in the over production of tau or β-amyloid. Biochemically significant mitochondrial defects do occur in AD and are likely to contribute to the overall central nervous system dysfunction in impairing neuronal function and possibly causing neurodegeneration via mechanisms other than apoptosis. [ABSTRACT FROM AUTHOR]