China
Africa
Explore chapters and articles related to this topic
Neurodegeneration, ataxia, and retinitis pigmentosa (NARP)
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
An expanded spectrum of NARP syndrome [14] was recognized when the 8993G mutation was found in a patient whose diagnosis on magnetic resonance imaging (MRI) was acute demyelinating encephalomyelitis (ADEM). The patient had neurogenic muscle weakness, and ataxia, typical for NARP, but other affected family members had fewer clinical manifestations. Nevertheless, his mother died of fulminant hepatic failure following valproate administration. In four families studied, none had retinitis pigmentosa. One was referred for “cerebral palsy”, attention deficit disorder, and learning disability. Later, he had episodes of ataxia, headache, and peripheral neuropathy following febrile illnesses.
Mitochondrial Pathologies and Their Neuromuscular Manifestations
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
Carlos Ortez, Andrés Nascimento
NARP syndrome is due to the transversion m.8993T>G and, less commonly, to the transition m.8993T>C in the MT-ATP6 gene, encoding subunit 6 of ATP synthase115. The T8993C mutation is generally considered to be less severe than the T8993G mutation. The clinical presentation of patients with heteroplasmic NARP mutations is dominated by proximal neurogenic muscle weakness with sensory neuropathy, ataxia due to cerebellar atrophy, epilepsy, learning difficulties and pigmentary retinopathy. Associated myopathy is rare and muscle biopsy is usually normal. Electromyography (EMG) and nerve conduction studies may demonstrate peripheral neuropathy (which may be a sensory or sensori-motor axonal polyneuropathy)116,117. Onset of symptoms is often in early childhood; individuals can be relatively stable for many years, but may suffer episodic deterioration. When the heteroplasmy level is higher than 80% patients frequently have a more early and severe impairment which is presented as Leigh syndrome. CMT2 related to MT-ATP6 mutation.
Inborn errors of metabolism
Published in Martin Andrew Crook, Clinical Biochemistry & Metabolic Medicine, 2013
There are a number of mitochondrial disorders, including Leigh’s syndrome, MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis, stroke), Kearns–Sayre syndrome, NARP syndrome (neuropathy, ataxia, retinitis pigmentosa) and LHON syndrome (Leber’s hereditary optic neuropathy).
Pharmacotherapeutic management of epilepsy in MERRF syndrome
Published in Expert Opinion on Pharmacotherapy, 2019
With increasing number of MERRF patients published, the spectrum of clinical presentations broadened and the phenotypic characteristics became increasingly heterogeneous (Table 1) [8,9]. In addition to the classical MERRF phenotype [6], MERRF-plus phenotypes (canonical features plus other manifestations) [52–64] can present as overlap between MERRF and progressive external ophthalmoplegia [59], MERRF and mitochondrial encephalopathy lactic acidosis and stroke-like episodes (MELAS) [55,58], MERRF and Kearns–Sayre syndrome (KSS) [61,62], MERRF and neuropathy ataxia and retinitis pigmentosa (NARP) syndrome [64], or MERRF and Leigh syndrome (LS) [6,52,56]. Patients with an overlap phenotype may carry a single variant or one variant each in two different genes or two variants in the same gene [65]. For example, strong intra-familial phenotypic heterogeneity of the m.8363G>A variant may manifest as LS in the daughter or as MERRF syndrome in the mother [56].