Alpers syndrome with mutations in POLG: clinical and investigative features.
ABSTRACT Alpers syndrome is a rare autosomal recessive hepatocerebral degenerative disorder. Seventeen patients with Alpers syndrome or polymerase-γ gene mutations were identified. Case records of 12 patients with Alpers syndrome and polymerase-γ mutations in both alleles were reviewed. All patients manifested developmental delay or regression, refractory epilepsy, and biochemical liver dysfunction. Liver failure occurred in three patients previously treated with valproate. Other signs included ataxia, visual disturbance, motor paresis, and tremor. Myoclonic and focal motor seizures were common, often manifesting as status epilepticus. Electroencephalograms demonstrated absent/slow posterior dominant rhythms. Interictal discharges were common, usually involving the occipital lobes. Rhythmic high-amplitude delta with (poly)spikes was evident in four patients. Magnetic resonance imaging showed migratory, cortical, and subcortical T(2) hyperintensities in four children most often affected the parietal and occipital lobes. Developmental regression and refractory focal motor or myoclonic seizures are consistent clinical features of Alpers syndrome with polymerase-γ mutations. Liver dysfunction constitutes a late manifestation. Migratory T(2)/fluid attenuated inversion recovery signal abnormalities involving metabolically active occipital and sensorimotor cortical regions comprise characteristic imaging findings. Interictal and ictal electroencephalogram patterns are more variable than previously reported. Three common polymerase-γ mutations, in patients of European descent, can assist with rapid diagnosis, circumventing the need for liver biopsy.
- SourceAvailable from: Lily Wong-Kisiel[Show abstract] [Hide abstract]
ABSTRACT: Epileptic encephalopathy syndromes are disorders in which the epileptiform abnormalities are thought to contribute to a progressive cerebral dysfunction. Characteristic electroencephalogram findings have an important diagnostic value in classification of epileptic encephalopathy syndromes. In this paper, we focus on electroencephalogram findings of childhood epileptic encephalopathy syndromes and provide sample illustrations.Epilepsy research and treatment. 01/2013; 2013:743203.
- [Show abstract] [Hide abstract]
ABSTRACT: Valproic acid (VPA) is widely used to treat epilepsy, migraine, chronic headache, bipolar disorder, and as adjuvant chemotherapy, but potentially causes idiosyncratic liver injury. Alpers syndrome (AHS), a neurometabolic disorder caused by mutations in the mitochondrial DNA polymerase gamma (POLG), is associated with an increased risk of developing fatal VPA hepatotoxicity. However, the mechanistic link of this clinical mystery remains unknown. Here, fibroblasts from two AHS patients were reprogrammed to induced pluripotent stem cells, and then differentiated to hepatocyte-like cells (AHS iPSCs-Hep). Both AHS iPSCs-Hep are more sensitive to VPA-induced mitochondrial dependent apoptosis than controls, showing more activated caspase-9 and cytochrome c release. Strikingly, levels of both soluble and oligomeric OPA1, which together keep cristae junctions tight, are reduced in AHS iPSCs-Hep. Furthermore, POLG mutation cells show reduced POLG expression, mitochondrial DNA (mtDNA) amount, mitochondrial ATP production as well as abnormal mitochondrial ultrastructure following differentiation to hepatocyte-like cells. Superoxide flashes, spontaneous bursts of superoxide generation, caused by opening of the mitochondrial permeability transition pore (mPTP), occur more frequently in AHS iPSCs-Hep. Moreover, the mPTP inhibitor, cyclosporine A (CsA), rescues VPA-induced apoptotic sensitivity in AHS iPSCs-Hep. This result suggests that targeting mPTP opening could be an effective method to prevent hepatotoxicity by VPA in AHS patients. In addition, carnitine or N-acetylcysteine (NAC), which has been used in the treatment of VPA-induced hepatotoxicity, is able to rescue VPA-induced apoptotic sensitivity in AHS iPSCs-Hep. Conclusion: AHS iPSCs-Hep are more sensitive to the VPA-induced mitochondrial dependent apoptotic pathway, and this effect is mediated by mPTP opening. This is the first toxicity model in genetic diseases using iPSCs, which also will enable the evaluation of drugs for the therapeutic target. This article is protected by copyright. All rights reserved.Hepatology 01/2015; · 11.19 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Three deceased infants from a Pakistani consanguineous family presented with a similar phenotype of cholestatic liver disease, hypotonia, severe failure to thrive, recurrent vomiting, renal tubulopathy, and a progressive neurodegenerative course. Mitochondrial DNA depletion syndrome was considered in view of multisystem involvement. Exome sequencing, revealed a homozygous novel mutation c.1183T>C (p.F395L) in exon 1 of the C10orf2 TWINKLE gene. The hepatocerebral phenotype is well recognized in association with recessive mutations involving the C10orf2 TWINKLE gene. The feature of renal tubulopathy adds to the multisystemic presentation in our patients and further demonstrates an expansion of the phenotype in mitochondrial DNA depletion syndrome associated with TWINKLE gene mutations. The absence of features of an epileptic encephalopathy appears to be of added interest.Molecular Genetics and Metabolism 12/2012; · 2.83 Impact Factor