Sengers syndrome: six novel AGK mutations in seven new families and review of the phenotypic and mutational spectrum of 29 patients

Background: Sengers syndrome is an autosomal recessive condition characterized by congenital cataract, hypertrophic cardiomyopathy, skeletal myopathy and lactic acidosis. Mutations in the acylglycerol kinase (AGK) gene have been recently described as the cause of Sengers syndrome in nine families. Methods: We investigated the clinical and molecular features of Sengers syndrome in seven new families; five families with the severe and two with the milder form. Results: Sequence analysis of AGK revealed compound heterozygous or homozygous predicted loss-of-function mutations in all affected individuals. A total of eight different disease alleles were identified, of which six were novel, homozygous c.523_524delAT (p.Ile175Tyrfs*2), c.424-1G > A (splice site), c.409C > T (p.Arg137*) and c.877 + 3G > T (splice site), and compound heterozygous c.871C > T (p.Gln291*) and c.1035dup (p.Ile346Tyrfs*39). All patients displayed perinatal or early-onset cardiomyopathy and cataract, clinical features pathognomonic for Sengers syndrome. Other common findings included blood lactic acidosis and tachydyspnoea while nystagmus, eosinophilia and cervical meningocele were documented in only either one or two cases. Deficiency of the adenine nucleotide translocator was found in heart and skeletal muscle biopsies from two patients associated with respiratory chain complex I deficiency. In contrast to previous findings, mitochondrial DNA content was normal in both tissues. Conclusion: We compare our findings to those in 21 previously reported AGK mutation-positive Sengers patients, confirming that Sengers syndrome is a clinically recognisable disorder of mitochondrial energy metabolism

Maladies par expansion de polyglutamine : données moléculaires et physiopathologiques

Dix ans se sont écoulés depuis l’identification d’une nouvelle classe de mutations responsables de maladies neurologiques héréditaires dues à la répétition d’un trinucléotide CAG dont la conséquence est une expansion de polyglutamine dans la protéine correspondante. Ce type de mutation, dite instable, est aujourd’hui impliqué dans neuf maladies neurodégénératives. Il a été proposé que l’expansion de polyglutamine pourrait conférer un gain de fonction à la protéine mutée et serait impliquée dans la mort neuronale par un mécanisme physiopathologique probablement com-mun à toutes les maladies par expansion de polyglutamine. La connaissance de certains des évènements impliqués dans le déclenchement du processus pathologique permet aujourd’hui d’envisager des cibles thérapeutiques, certaines d’entre elles sont d’ailleurs actuellement testées sur des modèles animaux et chez l’homme

Stuve-Wiedemann Syndrome: Is it Underrecognized?

Stuve-Wiedemann Syndrome (SWS) (OMIM #601559) is an autosomal recessive disorder characterized by skeletal changes, bowing of the lower limb, severe osteoporosis and joint contractures, episodic hyperthermia, frequent respiratory infections, feeding problems and high mortality in early life. It is caused by mutation in the leukemia inhibitory factor receptor gene (LIFR; 151443) on chromosome 5p13. We provide the clinical follow-up and molecular aspects of six new patients who carried the same novel mutation in the LIFR gene (p. Arg692X) and three patients carried a common haplotype at the LIFR locus supporting a founder effect in the Turkish population. The probable pathogenesis of the features is also discussed. Osseous findings in the presence of other above-mentioned morbid conditions should raise the suspicion of SWS in neonates especially in Arabic and Eastern Mediterranean countries with high rate of consanguineous marriages like in Turkey. Severe osteoporosis, bone deformities, milias, leukocoria, inflammatory lesions on distal extremities, tongue biting behavior and oral ulcers could be more prominent features of the survivors beyond the neonatal period while respiratory and feeding problems are remitting. It is of crucial importance to diagnose such babies earlier in order to prevent extensive laboratory workup and to provide proper genetic counseling. (C) 2014 Wiley Periodicals, Inc

Resveratrol attenuates oxidative stress in mitochondrial Complex I deficiency: Involvement of SIRT3

International audienceThe pathophysiological mechanisms underlying Complex I (CI) deficiencies are understood only partially which severely limits the treatment of this common, devastating, mitochondrial disorder. Recently, we have shown that resveratrol (RSV), a natural polyphenol, has beneficial effects on CI deficiency of nuclear origin. Here, we demonstrate that RSV is able to correct the biochemical defect in oxygen consumption in five of thirteen CI-deficient patient cell lines. Other beneficial effects of RSV include a decrease of total intracellular ROS and the up-regulation of the expression of mitochondrial superoxide dismutase (SOD2) protein, a key antioxidant defense enzyme. The molecular mechanisms leading to the up-regulation of SOD2 protein expression by RSV require the estrogen receptor (ER) and the estrogen-related receptor alpha (ERRα). Although RSV increases the level of SOD2 protein in patients' fibroblasts, the enzyme activity is not increased, in contrast to normal fibroblasts. This led us to hypothesize that SOD2 enzyme activity is regulated post-translationally. This regulation involves SIRT3, a mitochondrial NAD þ-dependent deacetylase and is critically dependent on NAD þ levels. Taken together, our data show that the metabolic effects of RSV combined with its antioxidant capacities makes RSV particularly interesting as a candidate molecule for the therapy of CI deficiencies

Linkage Disequilibrium between the Spinocerebellar Ataxia 3/Machado-Joseph Disease Mutation and Two Intragenic Polymorphisms, One of Which, X359Y, Affects the Stop Codon

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Distribution of ataxin-7 in normal human brain and retina

International audienceSpinocerebellar ataxia 7 (SCA7) is a neurodegenerative disease caused by the expansion of a CAG repeat encoding a polyglutamine tract in the protein ataxin-7. We developed antibodies directed against two different parts of the ataxin-7 protein and studied its distribution in brain and peripheral tissue from healthy subjects. Normal ataxin-7 was widely expressed in brain, retina and peripheral tissues, including striated muscle, testis and thyroid gland. In the brain, expression of ataxin-7 was not limited to areas in which neurones degenerate, and the level of expression was not related to the severity of neuronal loss. Immunoreactivity was low in some vulnerable populations of neurones, such as Purkinje cells. In neurones, ataxin-7 was found in the cell bodies and in processes. Nuclear labelling was also observed in some neurones, but was not related to the distribution of intranuclear inclusions observed in an SCA7 patient. In this patient, the proportion of neurones with nuclear labelling was higher, on average, in regions with neuronal loss. Double immunolabelling coupled with confocal microscopy showed that ataxin-7 colocalized with BiP, a marker of the endoplasmic reticulum, but not with markers of mitochondria or the trans-Golgi network

Spectrum of HNF1B Mutations in a Large Cohort of Patients Who Harbor Renal Diseases

Background and objectives: Hepatocyte nuclear factor 1β (HNF1β) is a transcription factor that is critical for the development of kidney and pancreas. In humans, mutations in HNF1B lead to congenital anomalies of the kidney and urinary tract, pancreas atrophy, and maturity-onset diabetes of the young type 5 and genital malformations

eKLIPse: a sensitive tool for the detection and quantification of mitochondrial DNA deletions from next-generation sequencing data

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