Padova, Italy
Padova, Italy

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Doimo M.,University of Padua | Desbats M.A.,University of Padua | Baldoin M.C.,University of Padua | Basso G.,University of Padua | And 7 more authors.
Human Mutation | Year: 2013

We studied eight kindreds with gyrate atrophy of choroid and retina (GA), a rare autosomal recessive disorder caused by mutations of the OAT gene, encoding the homoexameric enzyme ornithine-delta-aminotransferase. We identified four novel and five previously reported mutations. Missense alleles were expressed in yeast strain carrying a deletion of the orthologous of human OAT. All mutations markedly reduced enzymatic activity. However, the effect on the yeast growth was variable, suggesting that some mutations retain residual activity, below the threshold of the enzymatic assay. Mutant proteins were either highly unstable and rapidly degraded, or failed to assemble to form the active OAT hexamer. Where possible, fibroblast analysis confirmed these data. We found no correlation between the residual enzymatic activity and the age of onset, or the severity of symptoms. Moreover, the response to B6 was apparently not related to the specific mutations carried by patients. Overall these data suggest that other factors besides the specific OAT genotype modulate (GA) phenotype in patients. Finally, we found that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an AMPK activator known to increase mitochondrial biogenesis, markedly stimulates OAT expression, thus representing a possible treatment for a subset of GA patients with hypomorphic alleles. © 2012 Wiley Periodicals, Inc.

Desbats M.A.,University of Padua | Vetro A.,Biotechnology Research Laboratory | Limongelli I.,University of Pavia | Lunardi G.,University of Padua | And 15 more authors.
European Journal of Human Genetics | Year: 2015

Coenzyme Q 10 deficiency is a clinically and genetically heterogeneous disorder, with manifestations that may range from fatal neonatal multisystem failure, to adult-onset encephalopathy. We report a patient who presented at birth with severe lactic acidosis, proteinuria, dicarboxylic aciduria, and hepatic insufficiency. She also had dilation of left ventricle on echocardiography. Her neurological condition rapidly worsened and despite aggressive care she died at 23 h of life. Muscle histology displayed lipid accumulation. Electron microscopy showed markedly swollen mitochondria with fragmented cristae. Respiratory-chain enzymatic assays showed a reduction of combined activities of complex I+III and II+III with normal activities of isolated complexes. The defect was confirmed in fibroblasts, where it could be rescued by supplementing the culture medium with 10 μM coenzyme Q 10. Coenzyme Q 10 levels were reduced (28% of controls) in these cells. We performed exome sequencing and focused the analysis on genes involved in coenzyme Q 10 biosynthesis. The patient harbored a homozygous c.545T>G, p.(Met182Arg) alteration in COQ2, which was validated by functional complementation in yeast. In this case the biochemical and morphological features were essential to direct the genetic diagnosis. The parents had another pregnancy after the biochemical diagnosis was established, but before the identification of the genetic defect. Because of the potentially high recurrence risk, and given the importance of early CoQ 10 supplementation, we decided to treat with CoQ 10 the newborn child pending the results of the biochemical assays. Clinicians should consider a similar management in siblings of patients with CoQ10 deficiency without a genetic diagnosis. © 2015 Macmillan Publishers Limited All rights reserved.

Laszlo A.,University of Szeged | Elpeleg O.N.,Metabolic Disorders Unit | Horvath K.,Semmelweis University | Jakobs C.,Metabolic | And 8 more authors.
Ideggyogyaszati Szemle | Year: 2010

The authors summarize the pathomechanism of the myelination process, the clinical, radiological and the genetical aspects of the leukodystrophies, as in 18q deletion syndrome, adrenoleukodysrtophy, metachromatic leukodystrophy, Pelizaeus-Merzbacher leukodystrophy, Alexander disease and olivo-ponto- cerebellar atrophy (OPCA).

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