Search

We report the longest follow-up of clinical and biochemical features of two previously reported adult mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) patients treated with liver transplantation (LT), adding information on a third, recently transplanted, patient. All three patients overcame the early post-operative period and tolerated immunosuppressive therapy. Plasma nucleoside levels dramatically decreased, with evidence of clinical improvement of ambulation and neuropathy. Conversely, other features of MNGIE, as gastrointestinal dysmotility, low weight, ophthalmoparesis, and leukoencephalopathy were essentially unchanged. A similar picture characterized two patients treated with allogenic hematopoietic stem cell transplantation (AHSCT). In conclusion, LT promptly and stably normalizes nucleoside imbalance in MNGIE, stabilizing or improving some clinical parameters with marginal periprocedural mortality rate as compared to AHSCT. Nevertheless, restoring thymidine phosphorylase (TP) activity, achieved by both LT and AHSCT, does not allow a full clinical recovery, probably due to consolidated cellular damage and/or incomplete enzymatic tissue replacement.

Progressive external ophthalmoplegia (PEO), Kearns–Sayre syndrome (KSS) and Pearson syndrome are the three sporadic clinical syndromes classically associated with single large-scale deletions of mitochondrial DNA (mtDNA). PEO plus is a term frequently utilized in the clinical setting to identify patients with PEO and some degree of multisystem involvement, but a precise definition is not available. The purpose of the present study is to better define the clinical phenotypes associated with a single mtDNA deletion, by a retrospective study on a large cohort of 228 patients from the database of the “Nation-wide Italian Collaborative Network of Mitochondrial Diseases”. In our database, single deletions account for about a third of all patients with mtDNA-related disease, more than previously recognized. We elaborated new criteria for the definition of PEO and “KSS spectrum” (a category of which classic KSS represents the most severe extreme). The criteria for “KSS spectrum” include the resulting multisystem clinical features associated with the KSS features, and which therefore can predict their presence or subsequent development. With the new criteria, we were able to classify nearly all our single-deletion patients: 64.5% PEO, 31.6% KSS spectrum (including classic KSS 6.6%) and 2.6% Pearson syndrome. The deletion length was greater in KSS spectrum than in PEO, whereas heteroplasmy was inversely related with age at onset. We believe that the new phenotype definitions implemented here may contribute to a more homogeneous patient categorization, which will be useful in future cohort studies of natural history and clinical trials. © 2015, Springer-Verlag Berlin Heidelberg.

Mitochondria are implicated in several metabolic pathways including cell respiratory processes, apoptosis, and free radical production. Mitochondrial abnormalities have been documented in neurodegenerative diseases, including Alzheimer's, Parkinson's, and Huntington's diseases, and amyotrophic lateral sclerosis. Several studies have demonstrated that mitochondrial impairment plays an important role in the pathogenesis of this group of disorders. In this review, we discuss the role of mitochondria in the main neurodegenerative diseases and review the updated knowledge in this field.