Genomic technologies such as next-generation sequencing (NGS) are revolutionizing molecular diagnostics and clinical medicine. However, these approaches have proven inefficient at identifying pathogenic repeat expansions. Here, we apply a collection of bioinformatics tools that can be utilized to identify either known or novel expanded repeat sequences in NGS data. We performed genetic studies of a cohort of 35 individuals from 22 families with a clinical diagnosis of cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS). Analysis of whole-genome sequence (WGS) data with five independent algorithms identified a recessively inherited intronic repeat expansion [(AAGGG) exp ] in the gene encoding Replication Factor C1 (RFC1). This motif, not reported in the reference sequence, localized to an Alu element and replaced the reference (AAAAG) 11 short tandem repeat. Genetic analyses confirmed the pathogenic expansion in 18 of 22 CANVAS-affected families and identified a core ancestral haplotype, estimated to have arisen in Europe more than twenty-five thousand years ago. WGS of the four RFC1-negative CANVAS-affected families identified plausible variants in three, with genomic re-diagnosis of SCA3, spastic ataxia of the Charlevoix-Saguenay type, and SCA45. This study identified the genetic basis of CANVAS and demonstrated that these improved bioinformatics tools increase the diagnostic utility of WGS to determine the genetic basis of a heterogeneous group of clinically overlapping neurogenetic disorders.

A hexanucleotide repeat expansion in chromosome 9 open reading frame 72 (C9orf72) can cause amyotrophic lateral sclerosis (ALS) and/or frontotemporal dementia (FTD). We assessed its frequency in 781 sporadic ALS (sALS) and 155 familial ALS (fALS) cases, and in 248 Spanish controls. We tested the presence of the reported founder haplotype among mutation carriers and in 171 Ceph Europeans from Utah (CEU), 170 Yoruba Africans, 81 Han Chinese, and 85 Japanese subjects. The C9orf72 expansion was present in 27.1% of fALS and 3.2% of sALS. Mutation carriers showed lower age at onset (P = 0.04), shorter survival (P = 0.02), greater co‐occurrence of FTD (P = 8.2 × 10−5), and more family history of ALS (P = 1.4 × 10−20), than noncarriers. No association between alleles within the normal range and the risk of ALS was found (P = 0.12). All 61 of the mutation carriers were tested and a patient carrying 28 hexanucleotide repeats presented with the founder haplotype. This haplotype was found in 5.6% Yoruba Africans, 8.9% CEU, 3.9% Japanese, and 1.6% Han Chinese chromosomes.

Objective:Increasing number of neurological problems are being described in COVID-19 disease, but their frequency and type have not been defined. In this study we sought to determine the extent of neurological manifestations of COVID-19 in a prospective series of unselected patients admitted to the general medicine wards of our hospitals due to COVID-19 and who were examined by a team of neurologists.Methods:Eight neurologists provided medical attention to patients hospitalized for COVID-19 to provide medical support to other hospital units tasked with the care of an increasingly larger influx of COVID-19 patients. A series of 100 consecutive, unselected patients were evaluated systematically, including a questionnaire that collected medical information derived from the initial exam and the medical history.Results:Eighty-eight percent of the patients had one neurological manifestation associated with COVID-19 during hospitalization. Most common were anosmia-dysgeusia and headache (44% each), myalgias (43%), and dizziness (36%). Less frequent were encephalopathy (8%), syncope (7%), seizures (2%), and ischemic stroke during the period of hospitalization (2%). Anosmia and headache associated with younger patients with less severe disease, and both were associated with each other and with serum inflammatory markers. Encephalopathy was associated with fever and syncope and with markers of inflammation.Conclusions:Neurological disturbances are common in COVID-19 patients, particularly if patients are evaluated by neurologists. There is a wide variety of neurological conditions, some of them severe, in the spectrum of COVID-19 disease that will benefit from an evaluation by practicing neurologists.

ObjectiveTo report the clinical, neuroimaging, and antibody associations in patients with autoimmune encephalitis (AE) and thymoma.MethodsA retrospective cohort study of 43 patients was conducted. Antibody determination and immunoprecipitation to characterize novel antigens were performed using reported techniques.ResultsPatients' median age was 52 years (range: 23–88 years). Forty (93%) had neuronal surface antibodies: gamma-aminobutyric acid receptor A (GABAAR) (15), amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) (13), contactin-associated protein-like 2 (CASPR2) (4), leucine-rich, glioma inactivated 1 (LGI1) (3), glycine receptor (GlyR) (3), and unknown antigens (2). Concurrent antibodies against intracellular antigens occurred in 13 (30%; 9 anti–collapsin response mediator protein 5 [CRMP5]) and were more frequent in anti-AMPAR encephalitis (54% vs 20%; p = 0.037). The most common clinical presentation was encephalitis with multiple T2/fluid-attenuated inversion recovery hyperintense lesions in 23 (53%) patients (15 GABAAR, 5 AMPAR, and 1 unknown neuropil antibody), followed by encephalitis with peripheral nerve hyperexcitability in 7 (16%; 4 CASPR2, 2 LGI1, and 1 unknown antibody), limbic encephalitis in 6 (14%; 4 AMPAR, 1 LGI1, and 1 antibody negative), progressive encephalomyelitis with rigidity and myoclonus in 4 (9%; 3 GlyR and 1 AMPAR antibodies), and encephalitis with normal MRI in 3 (7%; AMPAR antibodies). Anti-GABAAR encephalitis was more prevalent in Japanese patients compared with Caucasians and other ethnicities (61% vs 16%; p = 0.003). In anti-AMPAR encephalitis, 3/4 patients with poor and 0/6 with good outcome had concurrent CRMP5 antibodies (p = 0.033). Immunoprecipitation studies identified metabotropic glutamate receptor 3 antibodies that were additionally found in 5 patients (3 with and 2 without encephalitis).ConclusionsAE in patients with thymoma include several clinical-radiologic syndromes that vary according to the associated antibodies. Anti-GABAAR encephalitis was the most frequent AE and occurred more frequently in Japanese patients.