We previously localized a new form of recessive ataxia with generalized tonic-clonic epilepsy and mental retardation to a 19 Mb interval in 16q21-q23 by homozygosity mapping of a large consanguineous Saudi Arabian family. We now report the identification by whole exome sequencing of the missense mutation changing proline 47 into threonine in the first WW domain of the WW domain containing oxidoreductase gene, WWOX, located in the linkage interval. Proline 47 is a highly conserved residue that is part of the WW motif consensus sequence and is part of the hydrophobic core that stabilizes the WW fold. We demonstrate that proline 47 is a key amino acid essential for maintaining the WWOX protein fully functional, with its mutation into a threonine resulting in a loss of peptide interaction for the first WW domain. We also identified another highly conserved homozygous WWOX mutation changing glycine 372 to arginine in a second consanguineous family. The phenotype closely resembled the index family, presenting with generalized tonic-clonic epilepsy, mental retardation and ataxia, but also included prominent upper motor neuron disease. Moreover, we observed that the short-lived Wwox knock-out mouse display spontaneous and audiogenic seizures, a phenotype previously observed in the spontaneous Wwox mutant rat presenting with ataxia and epilepsy, indicating that homozygous WWOX mutations in different species causes cerebellar ataxia associated with epilepsy.

Mutations in the synaptic nuclear envelope protein 1 (SYNE1) gene have been reported to cause a relatively pure, slowly progressive cerebellar recessive ataxia mostly identified in Quebec, Canada. Combining next-generation sequencing techniques and deep-phenotyping (clinics, magnetic resonance imaging, positron emission tomography, muscle histology), we here established the frequency, phenotypic spectrum and genetic spectrum of SYNE1 in a screening of 434 non-Canadian index patients from seven centres across Europe. Patients were screened by whole-exome sequencing or targeted panel sequencing, yielding 23 unrelated families with recessive truncating SYNE1 mutations (23/434 = 5.3%). In these families, 35 different mutations were identified, 34 of them not previously linked to human disease. While only 5/26 patients (19%) showed the classical SYNE1 phenotype of mildly progressive pure cerebellar ataxia, 21/26 (81%) exhibited additional complicating features, including motor neuron features in 15/26 (58%). In three patients, respiratory dysfunction was part of an early-onset multisystemic neuromuscular phenotype with mental retardation, leading to premature death at age 36 years in one of them. Positron emission tomography imaging confirmed hypometabolism in extra-cerebellar regions such as the brainstem. Muscle biopsy reliably showed severely reduced or absent SYNE1 staining, indicating its potential use as a non-genetic indicator for underlying SYNE1 mutations. Our findings, which present the largest systematic series of SYNE1 patients and mutations outside Canada, revise the view that SYNE1 ataxia causes mainly a relatively pure cerebellar recessive ataxia and that it is largely limited to Quebec. Instead, complex phenotypes with a wide range of extra-cerebellar neurological and non-neurological dysfunctions are frequent, including in particular motor neuron and brainstem dysfunction. The disease course in this multisystemic neurodegenerative disease can be fatal, including premature death due to respiratory dysfunction. With a relative frequency of ∼5%, SYNE1 is one of the more common recessive ataxias worldwide.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for coronavirus disease 2019 (COVID-19) led to the death of thousands of people around the world. 1 Neurologic manifestations are not much specific apart from acute anosmia, and postinfectious manifestation data are missing. 2 We described the cases of 2 patients exhibiting demyelinating form of Guillain-Barré syndrome (GBS) and summarized neurologic manifestations and investigations results in table 1.

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utosomal recessive cerebellar ataxias (ARCAs) correspond to a heterogeneous group of inherited neurodegenerative disorders that affect the cerebellum and/or the peripheral nerves. 1 A new classification of ARCA has been proposed including 3 groups: ARCA with pure sensory neuropathy, ARCA with sensorimotor axonal neuropathy, and ARCA without neuropathy. 2 Recently, a new form of ARCA due to mutations in the ANO10 gene has been reported. 3 To which group of the classification does this new entity belong and whether genotype-phenotype correlation may be proposed have not yet been elucidated. We report 9 unrelated patients carrying 8 novel ANO10 mutations, and we compared these patients with the 12 previously reported cases in order to provide the delineation of the disease and genotype-phenotype correlations. MethodsBetween 2010 and 2013, a total of 186 unrelated index patients were consecutively recruited from 4 tertiary centers for inherited neurodegenerative disorders. Inclusion criteria were the combination of (1) sporadic or recessive progressive cerebellar ataxia; (2) age at onset of younger than 50 years; and (3) unknown etiology despite extensive investigations, including molecular analysis for Friedreich ataxia and obvious forms of recessive ataxias. Written informed consent was obtained from all participants. Participants were not financially compensated. The recessive ataxia research project was approved by the Strasbourg ethics committee. A detailed neurological examination, including scales of severity and magnetic resonance imaging of the brain, was performed for all patients. IMPORTANCE ANO10 mutations have been reported to cause a novel form of autosomal recessive cerebellar ataxia (ARCA). Our objective was to report 9 ataxic patients carrying 8 novel ANO10 mutations to improve the delineation of this form of ARCA and provide genotype-phenotype correlation.OBSERVATIONS The ANO10 gene has been sequenced in 186 consecutive patients with ARCA. The detailed phenotype of patients with ANO10 mutations was investigated and compared with the 12 previously reported cases. The mean age at onset was 33 years (range, 17-43 years), and the disease progression was slow. Corticospinal tract signs were frequent, including extensor plantar reflexes and/or diffuse tendon reflexes and/or spasticity. No patient in our series had peripheral neuropathy. Magnetic resonance imaging of the brains of our patients revealed marked cerebellar atrophy. The most frequent mutation, a mononucleotide expansion from a polyA repeat tract (c.132dupA) that causes protein truncation, was never observed in homozygosity. Only 2 truncating mutations were reported in homozygosity, one of which (c.1150-1151del) was associated with juvenile or adolescent onset and mental retardation, whereas we show that the presence of at least 1 missense or in-frame mutation is associated with adult onset and slow progression.CONCLUSIONS AND RELEVANCE An ANO10 mutation is responsible for ARCA that is mainly characterized by cerebellar atrophy and lack of peri...

IMPORTANCE Ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive cerebellar ataxia due to mutations in the aprataxin gene (APTX) that is characterized by early-onset cerebellar ataxia, oculomotor apraxia, axonal motor neuropathy, and eventual decrease of albumin serum levels. OBJECTIVES To improve the clinical, biomarker, and molecular delineation of AOA1 and provide genotype-phenotype correlations. DESIGN, SETTING, AND PARTICIPANTS This retrospective analysis included the clinical, biological (especially regarding biomarkers of the disease), electrophysiologic, imaging, and molecular data of all patients consecutively diagnosed with AOA1 in a single genetics laboratory from

Our algorithm is highly sensitive and specific, accurately predicting the underlying molecular diagnoses of autosomal recessive cerebellar ataxias, thereby guiding targeted sequencing or facilitating interpretation of next-generation sequencing data. Ann Neurol 2017;82:892-899.