Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0016719 (Friedreich's ataxia)
 2,098 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypertrophic cardiomyopathy is associated with marked genetic and phenotypic heterogeneity. Pathogenic mutations in the 10 hypertrophic cardiomyopathy-associated sarcomeric genes cause autosomal dominant disease as a rule, although recessive disease has been reported. Cardiac hypertrophy is also a hallmark of Friedreich ataxia, an autosomal recessive disease caused by deficiency of the mitochondrial protein frataxin. We hypothesized that heterozygous mutations in frataxin may mimic or modify hypertrophic cardiomyopathy. Using DHPLC and DNA sequencing, we identified the novel R40C-frataxin mutation in a patient who also harbored a previously reported R810H-myosin binding protein C mutation. The R810H mutation is reported to cause hypertrophic cardiomyopathy only in the setting of homozygosity or compound heterozygosity with another sarcomeric mutation. Site-directed mutagenesis and in vitro and in vivo analysis enabled functional characterization of the mutant frataxin protein. R40C-frataxin protein is not cleaved to the mature form in vitro and shows delayed kinetics of cleavage by isolated mouse mitochondria. Yeast cells expressing R40C-frataxin demonstrated increased sensitivity to oxidative stress and abnormal accumulation of precursor frataxin protein. These data indicate that frataxin deficiency may have contributed to this patient's particular phenotype. Furthermore, these findings suggest that mutations altering myocyte energetics may act in synergy with sarcomeric mutations to cause hypertrophic cardiomyopathy.
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PMID:Molecular and functional characterization of a human frataxin mutation found in hypertrophic cardiomyopathy. 1593 68

Friedreich ataxia is an autosomal recessive neurodegenerative disorder caused by a GAA trinucleotide expansion in the first intron of the Friedreich ataxia gene (FRDA) that causes reduced synthesis of frataxin, a mitochondrial protein likely to be involved in biosynthesis of iron-sulfur clusters. This leads to increased oxidative stress, progressive loss of large sensory neurons, and hypertrophic cardiomyopathy. To elucidate the mechanisms regulating FRDA expression and to develop an in vivo assay for agents that might upregulate FRDA expression in a therapeutically relevant manner, we have generated transgenic mice with a BAC genomic reporter construct consisting of an in-frame fusion between FRDA and the gene coding for enhanced green fluorescent protein (EGFP). Production of full-length frataxin-EGFP fusion protein was demonstrated by immunoblotting. EGFP expression was observed as early as day E3.5 of development. Most tissues of adult transgenic mice were fluorescent. The level of FRDA-EGFP expression in peripheral blood, bone marrow, and cells obtained from enzymatically disaggregated tissues was quantitated by flow cytometry. There was a twofold increase in EGFP expression in mice homozygous for the transgene when compared to hemizygous mice. These transgenic mice are a valuable tool for the examination of spatial and temporal aspects of FRDA gene expression and for the preclinical evaluation of pharmacological inducers of FRDA expression in a whole-animal model. In addition, tissues from these mice should also be valuable for stem cell transplantation studies.
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PMID:Evaluation of an FRDA-EGFP genomic reporter assay in transgenic mice. 1596 84

Heart involvement in patients with Friedreich ataxia (FRDA) is a condition marked by inevitable progressive deterioration, with premature death. There is currently no specific treatment for FRDA. Recently, a therapy with idebenone, a short-chain coenzyme Q10 analogue, was reported to reduce left ventricular mass by 20% in about half of FRDA patients, but a double-blind placebo-controlled study did not fully confirm these results. In this case report, we present a 5-year follow-up of symmetrical concentric hypertrophic cardiomyopathy (HCM) in an FRDA patient treated with high-dose propranolol. The therapy resulted in a reduction in the thickness of the septal and posterior left ventricular walls and complete normalization of diffuse electrocardiographic repolarization abnormalities. To the best of our knowledge, this is the first such case to be reported in the literature, demonstrating the positive effects of high-dose beta-blocker treatment on heart involvement in patients with FRDA.
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PMID:High-dose beta-blocker hypertrophic cardiomyopathy therapy in a patient with Friedreich ataxia. 1623 5

Dilated cardiomyopathy, hypertrophic cardiomyopathy, and cardiac rhythm disturbances are important features of certain neuromuscular disorders in children, adolescents, and young adults. This article summarizes the cardiac features seen in patients with Duchenne muscular dystrophy, Becker muscular dystrophy, myotonic dystrophy, Friedreich's ataxia, and Emery-Dreifuss muscular dystrophy. The optimal management of these cardiac features remains contentious, but increasingly these patients are referred for routine cardiological assessment in the absence of symptoms. This article examines the value of routine screening and drug interventions for cardiac complications in asymptomatic and symptomatic individuals with neuromuscular disorders. We recommend a pragmatic approach, actively looking for cardiac conditions which will benefit from early intervention, but avoiding routine screening for asymptomatic conditions in which there is no evidence of benefit from early intervention.
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PMID:Cardiac monitoring and treatment for children and adolescents with neuromuscular disorders. 1697 70

Friedreich's ataxia (FA) is one of the genetic syndromes sometimes associated with diabetes and the most common hereditary ataxia. It is a autosomal recessive neurodegenerative disease, caused by a mutation in the FRDA gene, which originates decreased expression of frataxin, a mitochondrial protein involved in iron metabolism. The disorder is usually manifest in childhood and is characterised by ataxia, dysarthria, scoliosis and feet deformity. About two thirds of patients have hypertrophic cardiomyopathy, 10% have diabetes and 20% have another glucose homeostasis disorder. Both insulin resistance and beta-cell dysfunction are implicated in this patients' diabetes pathophysiology. The mean half-life is 35 years. Cause of death is usually related to cardiomyopathy or diabetes' complications. We report the case study of two twin sisters with 28 years old, in whom FA was diagnosed in the first decade, both of them with diabetes since their early twenties. A third sister with FA is reported, with no glucose homeostasis disorder. They also have two healthy male brothers. Based in this cases, the FA associated diabetes pathophysiology is discussed, concerning the therapeutic approach to these patients and to their diabetic relatives without neurologic symptoms. The role of molecular genetic testing and genetic counselling are also debated.
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PMID:[Friedreich ataxia and diabetes mellitus--family study]. 1668 89

Friedreich ataxia (FA) is an autosomal-recessive disease primarily characterized by progressive neurological disability. A significant proportion of patients also present with a hypertrophic cardiomyopathy, which may, in some cases, cause premature death. FA is caused by insufficient levels of the protein, frataxin, which is involved in mitochondrial iron metabolism. All patients carry at least one copy of an intronic GAA triplet-repeat expansion that interferes with frataxin transcription. Normal chromosomes contain up to 35 to 40 GAA triplets in an Alu sequence localized in the first intron of the frataxin gene; FA chromosomes carry from approx 70 to more than 1000 GAA triplets. The molecular diagnosis of FA is, therefore, based on the detection of this expansion, which is present in homozygosity in more than 95% of the cases. The remaining patients are heterozygous for the GAA expansion and carry a frataxin point mutation as the other pathogenic allele. The expanded GAA triplet repeat may be detected by polymerase chain reaction (PCR) amplification followed by agarose gel electrophoresis analysis. In our hands, carefully performed PCR testing, in particular, if fragment detection is enhanced by hybridization with a GAA oligonucleotide probe, is as effective in identifying patients and carriers as is Southern blot analysis of genomic DNA, and allows a more accurate sizing of the repeat. Furthermore, in the case of smaller expansions, the amplified fragment may be directly sequenced to identify very rare nonpathogenic variant repeats, such as GAAGGA. Sequence analysis of the five coding exons of the frataxin gene should be performed in clinically affected individuals who are heterozygous for an expanded GAA repeat to identify point mutations.
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PMID:Friedreich ataxia: Detection of GAA repeat expansions and frataxin point mutations. 1693 14

We report on a 19-year-old Russian man with Friedreich ataxia with an expanded GAA repeat. The symptoms include ataxia of the trunk and lower extremities, dysdiadochokinesia of the upper extremities with left side dominance, square wave jerks, dysarthria, decreased muscle tone, areflexia, hypesthesia, decreased vibration sense and weakness in the lower extremities, extensor plantar response, skeletal abnormalies, and hypertrophic cardiomyopathy. Somatosensory Evoked Potentials elicited by median nerve stimulation suggested involvement of the central pathways, including the posterior column with lateral dominance. Sural nerve biopsy showed a marked decrease in large myelinated fibers (120/mm2) and a moderate decrease in small myelinated fibers (1430/mm2) with normal density of unmyelinated fibers. Carbon dioxide laser stimulation of the upper limbs demonstrated "C-fiber component" toward Adelta fibers and a normal component toward C fibers. Immunohistochemical staining of a skin biopsy from the lateral malleolus for protein gene product 9.5 demonstrated a normal density (18/mm) of intraepidermal nerve fibers. To our knowledge, this is the first report using CO2 laser stimulation, skin biopsy, and sural nerve biopsy that unmyelinated fibers are not involved in Friedreich ataxia.
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PMID:[Neurological findings, neurophysiological examinations, and sural nerve biopsy in a case of Friedreich ataxia]. 1706 2

Hypertrophic cardiomyopathy is a common complication of Friedreich's ataxia (FRDA). Histological sections reveal abnormal cardiomyocytes, muscle fiber necrosis, reactive inflammation, and increased endomysial connective tissue. Scattered muscle fibers display perinuclear collections of minute iron-positive granules that lie in rows between myofibrils. Frataxin deficiency in FRDA causes mitochondrial iron dysmetabolism. We studied total iron and the iron-related proteins ferritin, mitochondrial ferritin, divalent metal transporter 1 (DMT1), and ferroportin in FRDA hearts by biochemical and histological techniques. Total iron in the left ventricular wall of FRDA patients (30.7+/-19.3 mg/100 g dry weight) was not significantly higher than normal (31.3+/-24.1 mg/100 g dry weight). Similarly, cytosolic holoferritin levels in FRDA hearts (230+/-172 microg/g wet weight) were not significantly elevated above normal (148+/-86 microg/g wet weight). The iron-positive granules exhibited immunoreactivity for cytosolic ferritin, mitochondrial ferritin, and ferroportin. Electron microscopy showed enhanced electron density of mitochondrial deposits after treatment with bismuth subnitrate supporting ferritin accumulation. The inflammatory cells in the endomysium were reactive for CD68, cytosolic ferritin, and the DMT1 isoform(s) translated from messenger ribonucleic acids containing iron-responsive elements (DMT1+). Progressive cardiomyopathy in FRDA is the likely result of iron-catalyzed mitochondrial damage followed by muscle fiber necrosis and a chronic reactive myocarditis.
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PMID:Iron and iron-responsive proteins in the cardiomyopathy of Friedreich's ataxia. 1713 88

Friedreich Ataxia (FRDA), the most frequent inherited ataxia, is not only characterized by progressive gait and limb ataxia, but in most cases is also accompanied by a severe hypertrophic cardiomyopathy. This life threatening symptom can be ameliorated by the administration of idebenone, a short chain quinone antioxidant, supporting additional evidence that oxidative stress plays a major role in the pathogenesis of this disease. In this study we analyze the combinatorial effect of different antioxidants on cell viability of FRDA fibroblasts and of RAT-1 immortalized fibroblasts exposed to oxidative stress. We find that an equimolar mixture of idebenone and vitamin E is more potent than each of the compound alone. Increased potency was also obtained with a novel synthetic antioxidant (Fe-Aox29) combining the active groups from both idebenone and vitamin E. These results indicate, that idebenone and vitamin E might act synergistically to counteract oxidative stress in fibroblasts from FRDA patients.
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PMID:Protective effects of Fe-Aox29, a novel antioxidant derived from a molecular combination of Idebenone and vitamin E, in immortalized fibroblasts and fibroblasts from patients with Friedreich Ataxia. 1747 63

Friedreich's ataxia is an autosomal recessive disorder characterized by spinocerebellar degeneration. It is caused by a mutation that consists of an unstable expansion of GAA repeats in the first intron of the gene encoding frataxin on chromosome 9 (9q13). We reported a case of hypertrophic cardiomyopathy associated with Friedreich's ataxia in a twenty year old patient.
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PMID:Hypertrophic cardiomyopathy in Friedreich's ataxia. 1765 92


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