| 1. |
- Berger, Itai, et al.
(författare)
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Intractable epilepsy of infancy due to homozygous mutation in the EFHC1 gene
- 2012
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Ingår i: Epilepsia. - : Wiley. - 0013-9580 .- 1528-1167. ; 53:8, s. 1436-1440
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The molecular etiology of primary intractable epilepsy in infancy is largely unknown. We studied a nonconsanguineous Moroccan-Jewish family, where three of their seven children presented with intractable seizures and died at 18-36 months.Methods: Homozygous regions were searched using 250 K DNA single nucleotide polymorphism (SNP) array. The sequence of 50 Mb exome of a single patient was determined using SOLiD 5500XL deep sequencing analyzer.Key Findings: A single homozygous 11.3 Mb genomic region on chromosome 6 was linked to the disease in this family. This region contained 110 genes encoding a total of 1,000 exons. Whole exome sequencing revealed a single pathogenic homozygous variant within the critical region. The mutation, Phe229Leu in the EFHC1 gene was previously shown, in a carrier state, to be associated with juvenile myoclonic epilepsy.Significance: Although heterozygosity for the Phe229Leu mutation is known to be associated with a relatively benign form of epilepsy in adolescence; homozygosity for the same mutation is associated with lethal epilepsy of infancy. Given the considerable carrier rate of this mutation worldwide, the sequence of the EFHC1 gene should be determined in all patients with primary intractable epilepsy in infancy.
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| 2. |
- Spiegel, Konen, et al.
(författare)
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Infantile Cerebellar-Retinal Degeneration Associated with a Mutation in Mitochondrial Aconitase, ACO2
- 2012
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Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 90:3, s. 518-523
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Tidskriftsartikel (refereegranskat)abstract
- Degeneration of the cerebrum, cerebellum, and retina in infancy is part of the clinical spectrum of lysosomal storage disorders, mitochondrial respiratory chain defects, carbohydrate glycosylation defects, and infantile neuroaxonal dystrophy. We studied eight individuals from two unrelated families who presented at 2-6 months of age with truncal hypotonia and athetosis, seizure disorder, and ophthalmologic abnormalities. Their course was characterized by failure to acquire developmental milestones and culminated in profound psychomotor retardation and progressive visual loss, including optic nerve and retinal atrophy. Despite their debilitating state, the disease was compatible with survival of up to 18 years. Laboratory investigations were normal, but the oxidation of glutamate by muscle mitochondria was slightly reduced. Serial brain MRI displayed progressive, prominent cerebellar atrophy accompanied by thinning of the corpus callosum, dysmyelination, and frontal and temporal cortical atrophy. Homozygosity mapping followed by whole-exome sequencing disclosed a Ser112Arg mutation in ACO2, encoding mitochondrial aconitase, a component of the Krebs cycle. Specific aconitase activity in the individuals' lymphoblasts was severely reduced. Under restrictive conditions, the mutant human ACO2 failed to complement a yeast ACO1 deletion strain, whereas the wild-type human ACO2 succeeded, indicating that this mutation is pathogenic. Thus, a defect in mitochondrial aconitase is associated with an infantile neurodegenerative disorder affecting mainly the cerebellum and retina. In the absence of noninvasive biomarkers, determination of the ACO2 sequence or of aconitase activity in lymphoblasts are warranted in similarly affected individuals, based on clinical and neuroradiologic grounds.
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| 3. |
- Spiegel, Ronen, et al.
(författare)
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Deleterious mutation in FDX1L gene is associated with a novel mitochondrial muscle myopathy
- 2014
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Ingår i: European Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 22:7, s. 902-906
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Tidskriftsartikel (refereegranskat)abstract
- Isolated metabolic myopathies encompass a heterogeneous group of disorders, with mitochondrial myopathies being a subgroup, with depleted skeletal muscle energy production manifesting either by recurrent episodes of myoglobinuria or progressive muscle weakness. In this study, we investigated the genetic cause of a patient from a consanguineous family who presented with adolescent onset autosomal recessive mitochondrial myopathy. Analysis of enzyme activities of the five respiratory chain complexes in our patients' skeletal muscle showed severely impaired activities of iron sulfur (Fe-S)-dependent complexes I, II and III and mitochondrial aconitase. We employed exome sequencing combined with homozygosity mapping to identify a homozygous mutation, c.1A > T, in the FDX1L gene, which encodes the mitochondrial ferredoxin 2 (Fdx2) protein. The mutation disrupts the ATG initiation translation site resulting in severe reduction of Fdx2 content in the patient muscle and fibroblasts mitochondria. Fdx2 is the second component of the Fe-S cluster biogenesis machinery, the first being IscU that is associated with isolated mitochondrial myopathy. We suggest adding genetic analysis of FDX1L in cases of mitochondrial myopathy especially when associated with reduced activity of the respiratory chain complexes I, II and III.
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