MERRF is an acronym of myoclonus epilepsy associated with ragged-red fibers and was first reported as a new nosological entity belonging to mitochondrial encephalomyopathies in San Remo symposium on "Mitochondrial Pathology" in 1982. MERRF was named Fukuhara disease by Rowland (1983). The first reported patient had been diagnosed as having Ramsay Hunt syndrome associated with Friedreich's ataxia. However, nowadays, the previously reported cases as having Ramsay Hunt syndrome associated with Friedreich's ataxia are regarded as having been suffered from MERRF. The history in establishing the nosological entity of MERRF was described. Patients with MERRF develop myoclonus, epileptic seizures, cerebellar ataxia, dementia, sensorineural hearing disturbance, optic atrophy, muscular wasting, and foot deformities at the advanced stage. Pathological findings show degeneration of the dentate nuclei, globus pallidus, and red nuclei, substantia nigra, inferior olivary nuclei, cerebellar cortex, and spinal cord. The posterior columns, the spinocerebellar tracts, and Clark's columns are degenerating in the spinal cord. The pyramidal tracts never show a severe degeneration as in Friedreich's ataxia. The skeletal muscles show mitochondrial abnormalities histologically and electron microscopically. Clinical features of MERRF are not necessarily uniform in the early stage and muscle biopsy findings are also very mild in some patients with MERRF, necessitating genetic analysis for diagnosis. Most of patients show a point mutation (A --> G) of nt 8344 in mitochondrial DNA.
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Mol Ther Methods Clin Dev
December 2024
Department of Neurology, O'Donnell Brain Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.
Friedreich's ataxia (FRDA) is a multisystem, autosomal recessive disorder caused by mutations in the frataxin () gene. As FRDA is considered an FXN deficiency disorder, numerous therapeutic approaches in development or clinical trials aim to supplement FXN or restore endogenous expression. These include gene therapy, protein supplementation, genome editing or upregulation of transcription.
View Article and Find Full Text PDFJ Neurol
January 2025
Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
Objective: This study aims to evaluate our experience in the diagnosis of hereditary ataxias (HAs), to analyze data from a real-world scenario.
Study Design: This is a retrospective, cross-sectional, descriptive study conducted at a single Italian adult neurogenetic outpatient clinic, in 147 patients affected by ataxia with a suspicion of hereditary forms, recruited from November 1999 to February 2024. A stepwise approach for molecular diagnostics was applied: targeted gene panel (TP) next-generation sequencing (NGS) and/or clinical exome sequencing (CES) were performed in the case of inconclusive first-line genetic testing, such as short tandem repeat expansions (TREs) testing for most common spinocerebellar ataxias (SCA1-3, 6-8,12,17, DRPLA), other forms [Fragile X-associated tremor/ataxia syndrome (FXTAS), Friedreich ataxia (FRDA) and mitochondrial DNA-related ataxia, RFC1-related ataxia/CANVAS] or inconclusive phenotype-guided specific single gene sequencing.
Neurol Ther
January 2025
Biohaven Pharmaceuticals, Inc., 215 Church Street, New Haven, CT, 06510, USA.
Introduction: The Friedreich Ataxia Rating Scale-Activities of Daily Living (FARS-ADL) is a validated and highly utilized measure for evaluating patients with Friedreich Ataxia. While construct validity of FARS-ADL has been shown for spinocerebellar ataxia (SCA), content validity has not been established.
Methods: Individuals with SCA1 or SCA3 (n = 7) and healthcare professionals (HCPs) with SCA expertise (n = 8) participated in qualitative interviews evaluating the relevance, clarity, and clinical meaningfulness of FARS-ADL for assessment of individuals with SCA.
Neurol Genet
February 2025
Department of Neurology and Neurosurgery, McGill University, Montreal, Canada.
In the late 1800s, Nikolaus Friedreich first described "degenerative atrophy of the posterior columns of the spinal cord," noting its connection to progressive ataxia, sensory loss, and muscle weakness, now recognized as Friedreich ataxia (FRDA). Renewed interest in the disease in the 1970s and 80s by the Quebec Cooperative Group and by Anita Harding led to the development of clinical diagnostic criteria and insights into associated biochemical abnormalities, although the primary defect remained unknown. In 1988, Susan Chamberlain mapped FRDA's location on chromosome 9.
View Article and Find Full Text PDFNeurodegener Dis Manag
January 2025
Perelman School of Medicine of the University of Pennsylvania, Philadelphia, PA, USA.
Friedreich ataxia (FRDA) is a slowly progressive neurological disease resulting from decreased levels of the protein frataxin, a small mitochondrial protein that facilitates the synthesis of iron-sulfur clusters in the mitochondrion. It is caused by GAA (guanine-adenine-adenine) repeat expansions in the gene in 96% of patients, with 4% of patients carrying other mutations (missense, nonsense, deletion) in the gene. Compound heterozygote patients with one expanded GAA allele and a non-GAA repeat mutation can have subtle differences in phenotype from typical FRDA, including, in patients with selected missense mutations, both more severe features and less severe features in the same patient.
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