Novel Autoantibodies in Idiopathic Small Fiber Neuropathy.

OBJECTIVE: Small fiber neuropathy (SFN) is clinically and etiologically heterogeneous. Although autoimmunity has been postulated to be pathophysiologically important in SFN, few autoantibodies have been described. We aimed to identify autoantibodies associated with idiopathic SFN (iSFN) by a novel high-throughput protein microarray platform that captures autoantibodies expressed in the native conformational state. METHODS: Sera from 58 SFN patients and 20 age- and gender-matched healthy controls (HCs) were screened against >1,600 immune-related antigens. Fluorescent unit readout and postassay imaging were performed, followed by composite data normalization and protein fold change (pFC) analysis. Analysis of an independent validation cohort of 33 SFN patients against the same 20 HCs was conducted to identify reproducible proteins in both cohorts. RESULTS: Nine autoantibodies were screened with statistical significance and pFC criteria in both cohorts, with at least 50% change in serum levels. Three proteins showed consistently high fold changes in main and validation cohorts: MX1 (FC = 2.99 and 3.07, respectively, p = 0.003, q = 0.076), DBNL (FC = 2.11 and 2.16, respectively, p = 0.009, q < 0.003), and KRT8 (FC = 1.65 and 1.70, respectively, p = 0.043, q < 0.003). Further subgroup analysis into iSFN and SFN by secondary causes (secondary SFN) in the main cohort showed that MX1 is higher in iSFN compared to secondary SFN (FC = 1.61 vs 0.106, p = 0.009). INTERPRETATION: Novel autoantibodies MX1, DBNL, and KRT8 are found in iSFN. MX1 may allow diagnostic subtyping of iSFN patients. ANN NEUROL 2022;91:66-77.

Expanding the genetic causes of small-fiber neuropathy: SCN genes and beyond.

Small-fiber neuropathy (SFN) is a disorder that exclusively affects the small nerve fibers, sparing the large nerve fibers. Thinly myelinated Aδ-fibers and unmyelinated C-fibers are damaged, leading to development of neuropathic pain, thermal dysfunction, sensory symptoms, and autonomic disturbances. Although many SFNs are secondary and due to immunological causes or metabolic disturbances, the etiology is unknown in up to half of the patients. Over the years, this proportion of "idiopathic SFN" has decreased, as familial and genetic causes have been discovered, thus shifting a proportion of once "idiopathic" cases to the genetic category. After the discovery of SCN9A-gene variants in 2012, SCN10A and SCN11A variants have been found to be pathogenic in SFN. With improved accessibility of SFN diagnostic tools and genetic tests, many non-SCN variants and genetically inherited systemic diseases involving the small nerve fibers have also been described, but only scattered throughout the literature. There are 80 SCN variants described as causing SFN, 8 genes causing hereditary sensory autonomic neuropathies (HSAN) described with pure SFN, and at least 7 genes involved in genetically inherited systemic diseases associated with SFN. This systematic review aims to consolidate and provide an updated overview on the genetic variants of SFN to date---SCN genes and beyond. Awareness of these genetic causes of SFN is imperative for providing treatment directions, prognostication, and management of expectations for patients and their health-care providers.

A multinational, multicentre study on the psychological outcomes and associated physical symptoms amongst healthcare workers during COVID-19 outbreak.

OBJECTIVE: Since the declaration of the coronavirus 2019 (COVID-19) outbreak as pandemic, there are reports on the increased prevalence of physical symptoms observed in the general population. We investigated the association between psychological outcomes and physical symptoms among healthcare workers. METHODS: Healthcare workers from 5 major hospitals, involved in the care for COVID-19 patients, in Singapore and India were invited to participate in a study by performing a self-administered questionnaire within the period of February 19 to April 17, 2020. Healthcare workers included doctors, nurses, allied healthcare workers, administrators, clerical staff and maintenance workers. This questionnaire collected information on demographics, medical history, symptom prevalence in the past month, Depression Anxiety Stress Scales (DASS-21) and the Impact of Events Scale-Revised (IES-R) instrument. The prevalence of physical symptoms displayed by healthcare workers and the associations between physical symptoms and psychological outcomes of depression, anxiety, stress, and post-traumatic stress disorder (PTSD) were evaluated. RESULTS: Out of the 906 healthcare workers who participated in the survey, 48 (5.3%) screened positive for moderate to very-severe depression, 79 (8.7%) for moderate to extremely-severe anxiety, 20 (2.2%) for moderate to extremely-severe stress, and 34 (3.8%) for moderate to severe levels of psychological distress. The commonest reported symptom was headache (32.3%), with a large number of participants (33.4%) reporting more than four symptoms. Participants who had experienced symptoms in the preceding month were more likely to be older, have pre-existing comorbidities and a positive screen for depression, anxiety, stress, and PTSD. After adjusting for age, gender and comorbidities, it was found that depression (OR 2.79, 95% CI 1.54-5.07, p = 0.001), anxiety (OR 2.18, 95% CI 1.36-3.48, p = 0.001), stress (OR 3.06, 95% CI 1.27-7.41, p = 0.13), and PTSD (OR 2.20, 95% CI 1.12-4.35, p = 0.023) remained significantly associated with the presence of physical symptoms experienced in the preceding month. Linear regression revealed that the presence of physical symptoms was associated with higher mean scores in the IES-R, DASS Anxiety, Stress and Depression subscales. CONCLUSIONS: Our study demonstrates a significant association between the prevalence of physical symptoms and psychological outcomes among healthcare workers during the COVID-19 outbreak. We postulate that this association may be bi-directional, and that timely psychological interventions for healthcare workers with physical symptoms should be considered once an infection has been excluded.

Mitochondrial dysfunction in neurodegenerative disorders.

Recent advances in understanding the role of mitochondrial dysfunction in neurodegenerative diseases have expanded the opportunities for neurotherapeutics targeting mitochondria to alleviate symptoms and slow disease progression. In this review, we offer a historical account of advances in mitochondrial biology and neurodegenerative disease. Additionally, we summarize current knowledge of the normal physiology of mitochondria and the pathogenesis of mitochondrial dysfunction, the role of mitochondrial dysfunction in neurodegenerative disease, current therapeutics and recent therapeutic advances, as well as future directions for neurotherapeutics targeting mitochondrial function. A focus is placed on reactive oxygen species and their role in the disruption of telomeres and their effects on the epigenome. The effects of mitochondrial dysfunction in the etiology and progression of Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and Huntington's disease are discussed in depth. Current clinical trials for mitochondria-targeting neurotherapeutics are discussed.

Co-occurrence of VHL and SDHA Pathogenic Variants: A Case Report.

Von Hippel Lindau(VHL)syndrome presents with cerebellar and spinal hemangioblastomas, renal cell cancer, neuroendocrine pancreatic tumor, and pheochromocytoma and it is caused by germline mutations in the VHL gene. Pathogenic germline variants in the succinate dehydrogenase A (SDHA) gene are associated with paraganglioma and pheochromocytoma. Here we report co-occurrence of germline pathogenic variants in both VHL and SDHA genes in a patient who presented with pancreatic neuroendocrine tumor. As these genes converge on the pseudo-hypoxia signaling pathway, further studies are warranted to determine the significance of co-occurrence of these variants in relation to tumor penetrance, disease severity, treatment response and clinical outcomes in this selected group of patients.

Retinal ciliopathies through the lens of Bardet-Biedl Syndrome: Past, present and future.

The primary cilium is a highly specialized and evolutionary conserved organelle in eukaryotes that plays a significant role in cell signaling and trafficking. Over the past few decades tremendous progress has been made in understanding the physiology of cilia and the underlying pathomechanisms of various ciliopathies. Syndromic ciliopathies consist of a group of disorders caused by ciliary dysfunction or abnormal ciliogenesis. These disorders have multiorgan involvement in addition to retinal degeneration underscoring the ubiquitous distribution of primary cilia in different cell types. Genotype-phenotype correlation is often challenging due to the allelic heterogeneity and pleiotropy of these disorders. In this review, we discuss the clinical and genetic features of syndromic ciliopathies with a focus on Bardet-Biedl syndrome (BBS) as a representative disorder. We discuss the structure and function of primary cilia and their role in retinal photoreceptors. We describe the progress made thus far in understanding the functional and genetic characterization including expression quantitative trait locus (eQTL) analysis of BBS genes. In the future directions section, we discuss the emerging technologies, such as gene therapy, as well as anticipated challenges and their implications in therapeutic development for ciliopathies.

TBX3 and EFNA4 Variant in a Family with Ulnar-Mammary Syndrome and Sagittal Craniosynostosis.

Ulnar-mammary syndrome (UMS) is a rare, autosomal dominant disorder characterized by anomalies affecting the limbs, apocrine glands, dentition, and genital development. This syndrome is caused by haploinsufficiency in the T-Box3 gene (TBX3), with considerable variability in the clinical phenotype being observed even within families. We describe a one-year-old female with unilateral, postaxial polydactyly, and bilateral fifth fingernail duplication. Next-generation sequencing revealed a novel, likely pathogenic, variant predicted to affect the canonical splice site in intron 3 of the TBX3 gene (c.804 + 1G > A, IVS3 + 1G > A). This variant was inherited from the proband's father who was also diagnosed with UMS with the additional clinical finding of congenital, sagittal craniosynostosis. Subsequent whole genome analysis in the proband's father detected a variant in the EFNA4 gene (c.178C > T, p.His60Tyr), which has only been reported to be associated with sagittal craniosynostosis in one patient prior to this report but reported in other cranial suture synostosis. The findings in this family extend the genotypic spectrum of UMS, as well as the phenotypic spectrum of EFNA4-related craniosynostosis.

Anti-phospholipid syndrome and COVID-19 thrombosis: connecting the dots.

As the coronavirus disease 2019 (COVID-19) pandemic, which is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is spreading rapidly worldwide, it has emerged as a leading cause of mortality, resulting in >1 million deaths over the past 10 months. The pathophysiology of COVID-19 remains unclear, posing a great challenge to the medical management of patients. Recent studies have reported an unusually high prevalence of thromboembolic events in COVID-19 patients, although the mechanism remains elusive. Several studies have reported the presence of aPLs in COVID-19 patients. We have noticed similarities between COVID-19 and APS, which is an autoimmune prothrombotic disease that is often associated with an infective aetiology. Molecular mimicry and endothelial dysfunction could plausibly explain the mechanism of thrombogenesis in acquired APS. In this review, we discuss the clinicopathological similarities between COVID-19 and APS, and the potential role of therapeutic targets based on the anti-phospholipid model for COVID-19 disease.