Multi-omics profiling reveals dysregulated ribosome biogenesis and impaired cell proliferation following knockout of CDR2L.

BACKGROUND: Cerebellar degeneration-related (CDR) proteins are associated with paraneoplastic cerebellar degeneration (PCD) - a rare, neurodegenerative disease caused by tumour-induced autoimmunity against neural antigens resulting in degeneration of Purkinje neurons in the cerebellum. The pathogenesis of PCD is unknown, in large part due to our limited understanding of the functions of CDR proteins. To this end, we performed an extensive, multi-omics analysis of CDR-knockout cells focusing on the CDR2L protein, to gain a deeper understanding of the properties of the CDR proteins in ovarian cancer. METHODS: Ovarian cancer cell lines lacking either CDR1, CDR2, or CDR2L were analysed using RNA sequencing and mass spectrometry-based proteomics to assess changes to the transcriptome, proteome and secretome in the absence of these proteins. RESULTS: For each knockout cell line, we identified sets of differentially expressed genes and proteins. CDR2L-knockout cells displayed a distinct expression profile compared to CDR1- and CDR2-knockout cells. Knockout of CDR2L caused dysregulation of genes involved in ribosome biogenesis, protein translation, and cell cycle progression, ultimately causing impaired cell proliferation in vitro. Several of these genes showed a concurrent upregulation at the transcript level and downregulation at the protein level. CONCLUSIONS: Our study provides the first integrative multi-omics analysis of the impact of knockout of the CDR genes, providing both new insights into the biological properties of the CDR proteins in ovarian cancer, and a valuable resource for future investigations into the CDR proteins.

Development and Optimization of a Multilayer Rat Purkinje Neuron Culture.

Elucidation of the mechanisms involved in neurodegenerative diseases of the cerebellum has been hampered by the lack of robust single cell models to study Purkinje neurons and replicate at the same time in vivo features. Cerebellar Purkinje neurons are difficult to grow in dispersed cell culture, and only limited work has been done using rat cells. We developed a refined protocol for growing rat Purkinje neurons from embryonic and postnatal tissue ex vivo that results in well-developed, mature, functional, and synaptically active neurons. The rat Purkinje neurons generated are responsive to paracrine factors and genetic manipulation, allowing great experimental flexibility at the single-cell level. This ex vivo model can be used to investigate disease mechanisms that disturb Purkinje neuron morphology, function, and communication in high- and low-throughput screening formats.

A cerebellar degeneration-related protein 2-like cell-based assay for anti-Yo detection in patients with paraneoplastic cerebellar degeneration.

BACKGROUND AND PURPOSE: Commercially available tests for Yo antibody detection have low specificity for paraneoplastic cerebellar degeneration (PCD) because these assays use cerebellar degeneration-related protein 2 (CDR2) as the antigen, not CDR2-like (CDR2L). We aimed to test the hypothesis that use of a CDR2L cell-based assay (CBA), as an additional screening technique, would increase the accuracy of Yo-PCD diagnosis. METHODS: An in-house CBA to test for anti-CDR2L antibodies was developed and used to screen sera from 48 patients with confirmed anti-Yo-associated PCD. Fifteen non-Yo PCD patients, 22 patients with ovarian cancer without neurological syndromes, 50 healthy blood donors, 10 multiple sclerosis, 15 Parkinson's disease, and five non-paraneoplastic ataxic patients were included as controls. Sera were also tested by western blot analysis using recombinant CDR2 and CDR2L proteins developed in house, by the commercially available line immunoassays from Ravo Diagnostika and Euroimmun, and by the CDR2 CBA from Euroimmun. RESULTS: The CDR2L CBA identified all 48 patients with Yo-PCD. No CDR2L CBA reaction was observed in any of the control sera. The western blot technique had lower sensitivity and specificity as sera from eight and six of the 48 Yo-PCD patients did not react with recombinant CDR2 or CDR2L, respectively. CONCLUSIONS: The CDR2L CBA is highly reliable for identification of Yo-PCD. Although our findings indicate that, currently, the combination of CDR2 and CDR2L yields the most reliable test results, it remains to be evaluated if a test for single anti-CDR2L positivity will serve as a sufficient biomarker for Yo-PCD diagnosis.

[A man in his fifties with near-syncope episodes and persistent dizziness]. / En mann i 50-årene med nærbesvimelser og vedvarende svimmelhet.

BACKGROUND: A previously healthy male patient in his fifties presented with subacute onset of severe, diffuse dysautonomia with orthostatic hypotension as the main symptom. A lengthy interdisciplinary workup revealed a rare condition. CASE PRESENTATION: Over the course of a year, the patient was twice admitted to the local department of internal medicine because of severe hypotension. Testing showed severe orthostatic hypotension with normal cardiac function tests and no apparent underlying cause. On referral to neurological examination, symptoms of a broader autonomic dysfunction were discovered, with symptoms of xerostomia, irregular bowel habits, anhidrosis and erectile dysfunction. The neurological examination was normal, except for bilateral mydriatic pupils. The patient was tested for ganglionic acetylcholine receptor (gAChR) antibodies. A strong positive result confirmed the diagnosis of autoimmune autonomic ganglionopathy. There were no signs of underlying malignancy. The patient received induction treatment with intravenous immunoglobulin and later maintenance treatment with rituximab, resulting in significant clinical improvement. INTERPRETATION: Autoimmune autonomic ganglionopathy is a rare but likely underdiagnosed condition, which may cause limited or widespread autonomic failure. Approximately half of the patients have ganglionic acetylcholine receptor antibodies in serum. It is important to diagnose the condition as it can cause high morbidity and mortality, but responds to immunotherapy.

Serum neurofilament as a predictor of 10-year grey matter atrophy and clinical disability in multiple sclerosis: a longitudinal study.

BACKGROUND: The predictive value of serum neurofilament light chain (sNfL) on long-term prognosis in multiple sclerosis (MS) is still unclear. OBJECTIVE: Investigate the relation between sNfL levels over a 2-year period in patients with relapsing-remitting MS, and clinical disability and grey matter (GM) atrophy after 10 years. METHODS: 85 patients, originally enrolled in a multicentre, randomised trial of ω-3 fatty acids, participated in a 10-year follow-up visit. sNfL levels were measured by Simoa quarterly until month 12, and then at month 24. The appearance of new gadolinium-enhancing (Gd+) lesions was assessed monthly between baseline and month 9, and then at months 12 and 24. At the 10-year follow-up visit, brain atrophy measures were obtained using FreeSurfer. RESULTS: Higher mean sNfL levels during early periods of active inflammation (Gd+ lesions present or recently present) predicted lower total (ß=-0.399, p=0.040) and deep (ß=-0.556, p=0.010) GM volume, lower mean cortical thickness (ß=-0.581, p=0.010) and higher T2 lesion count (ß=0.498, p=0.018). Of the clinical outcomes, higher inflammatory sNfL levels were associated with higher disability measured by the dominant hand Nine-Hole Peg Test (ß=0.593, p=0.004). Mean sNfL levels during periods of remission (no Gd+ lesions present or recently present) did not predict GM atrophy or disability progression. CONCLUSION: Higher sNfL levels during periods of active inflammation predicted more GM atrophy and specific aspects of clinical disability 10 years later. The findings suggest that subsequent long-term GM atrophy is mainly due to neuroaxonal degradation within new lesions.

Neurosarcoidosis - a patient series. / Nevrosarkoidose ­ en pasientserie.

BACKGROUND: Neurosarcoidosis is a rare form of sarcoidosis that affects the nervous system. The aim of the study was to survey clinical manifestations, findings from assessments and treatment strategies for patients with neurosarcoidosis. MATERIAL AND METHOD: The study performed a retrospective assessment of 17 patients with definitive, probable and possible neurosarcoidosis diagnosed in the period 2008-2019 at the Department of Neurology, Haukeland University Hospital. RESULTS: The average prevalence of definitive, probable or possible neurosarcoidosis in Norway's Vestland county was 2.7 per 100 000 inhabitants in the period in question. Onset took the form of central nervous affection (8 of 17), hydrocephalus (5 of 17) and cranial neuropathy (5 of 17). Sarcoidosis-like findings were made in 14 of 17 patients by means of contrast-enhanced magnetic resonance tomography (MRT) of the central nervous system, in 7 of 8 patients by positron emission tomography (PET), and in 12 of 16 patients by computed tomography (CT) of the thorax. There were cerebrospinal fluid abnormalities in 15 of 15 patients, with biopsy verification for 13 of 15. The symptoms of 16 of 17 patients improved or stabilised with prednisolone and/or other immunotherapy. INTERPRETATION: Neurosarcoidosis affects both the central and the peripheral nervous system. Cerebrospinal fluid analysis and contrast-enhanced MRT are important means of detecting inflammation. A biopsy is necessary for making a definitive diagnosis, but is not always feasible. PET can be used as a supplement to other examinations to assess various organ manifestations and to pinpoint biopsy sites. Corticosteroid therapy, and in some cases other immunotherapy, elicits a good response.

CDR2L Is the Major Yo Antibody Target in Paraneoplastic Cerebellar Degeneration.

The pathogenesis of Yo-mediated paraneoplastic cerebellar degeneration (PCD) is unclear. We applied cerebrospinal fluid and serum from PCD patients as well as CDR2 and CDR2L antibodies to neuronal tissue, cancer cell lines, and cells transfected with recombinant CDR2 and CDR2L to elucidate which is the major antigen of Yo antibodies. We found that Yo antibodies bound endogenous CDR2L, but not endogenous CDR2. However, Yo antibodies can bind the recombinant CDR2 protein used in routine clinical testing for these antibodies. Because Yo antibodies only bind endogenous CDR2L, we conclude that CDR2L is the major antigen of Yo antibodies in PCD. ANN NEUROL 2019;86:316-321.

Optimization of Receptor Occupancy Assays in Mass Cytometry: Standardization Across Channels with QSC Beads.

Receptor occupancy, the ratio between amount of drug bound and amount of total receptor on single cells, is a biomarker for treatment response to therapeutic monoclonal antibodies. Receptor occupancy is traditionally measured by flow cytometry. However, spectral overlap in flow cytometry limits the number of markers that can be measured simultaneously. This restricts receptor occupancy assays to the analysis of major cell types, although rare cell populations are of potential therapeutic relevance. We therefore developed a receptor occupancy assay suitable for mass cytometry. Measuring more markers than currently available in flow cytometry allows simultaneous receptor occupancy assessment and high-parameter immune phenotyping in whole blood, which should yield new insights into disease activity and therapeutic effects. However, varying sensitivity across the mass cytometer detection range may lead to misinterpretation of the receptor occupancy when drug and receptor are detected in different channels. In this report, we describe a method for optimization of mass cytometry receptor occupancy measurements by using antibody-binding quantum simply cellular (QSC) beads for standardization across channels with different sensitivities. We evaluated the method in a mass cytometry-based receptor occupancy assay for natalizumab, a therapeutic antibody used in multiple sclerosis treatment that binds to α4-integrin, which is expressed on leukocyte cell surfaces. Peripheral blood leukocytes from a treated patient were stained with a panel containing metal-conjugated antibodies for detection of natalizumab and α4-integrin. QSC beads with known antibody binding capacity were stained with the same metal-conjugated antibodies and were used to standardize the signal intensity in the leukocyte sample before calculating receptor occupancy. We found that QSC bead standardization across channels corrected for sensitivity differences for detection of drug and receptor and generated more accurate results than observed without standardization. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

The kynurenine pathway and cognitive performance in community-dwelling older adults. The Hordaland Health Study.

INTRODUCTION: Tryptophan, its downstream metabolites in the kynurenine pathway and neopterin have been associated with inflammation and dementia. We aimed to study the associations between plasma levels of these metabolites and cognitive function in community-dwelling, older adults. METHODS: This cross-sectional study included 2174 participants aged 70-72 years of the community-based Hordaland Health Study. Tryptophan, kynurenine, neopterin and eight downstream kynurenines were measured in plasma. Kendrick Object Learning Test (KOLT), Digit Symbol Test (DST) and the Controlled Oral Word Association Test (COWAT) were all outcomes in standardized Zellner's regression. The Wald test of a composite linear hypothesis of an association with each metabolite was adjusted by the Bonferroni method. Age, body mass index, C-reactive protein, depressive symptoms, diabetes, education, glomerular filtration rate, hypertension, previous myocardial infarction, prior stroke, pyridoxal 5'phosphate, sex and smoking were considered as potential confounders. RESULTS: Higher levels of the kynurenine-to-tryptophan ratio (KTR) and neopterin were significantly associated with poorer, overall cognitive performance (p < 0.002). Specifically, KTR was negatively associated with KOLT (ß -0.08, p = 0.001) and COWAT (ß -0.08, p = 0.001), but not with DST (ß -0.03, p = 0.160). This pattern was also seen for neopterin (KOLT: ß -0.07; p = 0.001; COWAT: ß -0.06, p = 0.010; DST: ß -0.01, p = 0.800). The associations were not confounded by the examined variables. No significant associations were found between the eight downstream kynurenines and cognition. CONCLUSION: Higher KTR and neopterin levels, biomarkers of cellular immune activation, were associated with reduced cognitive performance, implying an association between the innate immune system, memory, and language.

Cerebellar degeneration-related proteins 2 and 2-like are present in ovarian cancer in patients with and without Yo antibodies.

BACKGROUND: Cerebellar degeneration-related protein 2 (CDR2) has been presumed to be the main antigen for the onconeural antibody Yo, which is strongly associated with ovarian cancer and paraneoplastic cerebellar degeneration (PCD). Recent data show that Yo antibodies also target the CDR2-like protein (CDR2L). We, therefore, examined the expression of CDR2 and CDR2L in ovarian cancer tissue from patients with and without Yo antibodies and from various other cancerous and normal human tissues. METHODS: Ovarian cancer tissue and serum samples from 16 patients were included in the study (four with anti-Yo and PCD, two with anti-Yo without PCD, five with only CDR2L antibodies, and five without onconeural antibodies). Clinical data were available for all patients. The human tissues were examined by western blot and immunohistochemistry using rabbit CDR2 and CDR2L antibodies. RESULTS: Ovarian cancers from all 16 patients expressed CDR2 and CDR2L proteins. Both proteins were also present in normal and cancer tissue from mammary tissue, kidney, ovary, prostate, and testis. CONCLUSION: CDR2L is present in ovarian cancers from patients with and without Yo antibodies as was shown previously for CDR2. In addition, both CDR2 and CDR2L proteins are more widely expressed than previously thought, both in normal and cancerous tissues.

[Multiple sclerosis - a mitochondria-mediated disease?] / Multippel sklerose ­ en mitokondriemediert sykdom?

BACKGROUND Mitochondria play an important role in the pathogenesis of various neurodegenerative disorders, including Parkinson's disease. Neurodegenerative changes occur early in the course of multiple sclerosis (MS). This article aims to present information on a possible association between mitochondrial dysfunction and multiple sclerosis.MATERIAL AND METHOD The article is based on original and review articles selected following a literature search in PubMed, restricted to articles written in English, and concluded in May 2016. The literature search resulted in a total of 2276 articles. After a discretionary evaluation by the authors, 71 articles were read in full. Of these, 19 were used as references. In addition, we included 15 articles from reference lists and seven from the authors' own literature archive.RESULTS Mitochondrial changes have been demonstrated in affected areas of the brains of patients with MS. Although some of the changes may be attributed to mitochondrial damage that is secondary to inflammation, others may be compensatory due to the increased energy demands of demyelinated axons. The type of mitochondrial damage varies and is dependent on the pathology that triggers it.INTERPRETATION Mitochondrial damage secondary to inflammation, combined with increased energy demands secondary to demyelination, may result in a chronic energy deficiency in the central nervous system. This in turn may lead to neurodegeneration. Improved knowledge of the role of mitochondria in MS, both secondary to inflammation and possibly as a direct contributor to neurodegeneration, may provide a better understanding of the pathogenesis of the disease and perhaps contribute to new treatment options.

Multicentre comparison of a diagnostic assay: aquaporin-4 antibodies in neuromyelitis optica.

OBJECTIVE: Antibodies to cell surface central nervous system proteins help to diagnose conditions which often respond to immunotherapies. The assessment of antibody assays needs to reflect their clinical utility. We report the results of a multicentre study of aquaporin (AQP) 4 antibody (AQP4-Ab) assays in neuromyelitis optica spectrum disorders (NMOSD). METHODS: Coded samples from patients with neuromyelitis optica (NMO) or NMOSD (101) and controls (92) were tested at 15 European diagnostic centres using 21 assays including live (n=3) or fixed cell-based assays (n=10), flow cytometry (n=4), immunohistochemistry (n=3) and ELISA (n=1). RESULTS: Results of tests on 92 controls identified 12assays as highly specific (0-1 false-positive results). 32 samples from 50 (64%) NMO sera and 34 from 51 (67%) NMOSD sera were positive on at least two of the 12 highly specific assays, leaving 35 patients with seronegative NMO/spectrum disorder (SD). On the basis of a combination of clinical phenotype and the highly specific assays, 66 AQP4-Ab seropositive samples were used to establish the sensitivities (51.5-100%) of all 21 assays. The specificities (85.8-100%) were based on 92 control samples and 35 seronegative NMO/SD patient samples. CONCLUSIONS: The cell-based assays were most sensitive and specific overall, but immunohistochemistry or flow cytometry could be equally accurate in specialist centres. Since patients with AQP4-Ab negative NMO/SD require different management, the use of both appropriate control samples and defined seronegative NMOSD samples is essential to evaluate these assays in a clinically meaningful way. The process described here can be applied to the evaluation of other antibody assays in the newly evolving field of autoimmune neurology.

Paraneoplastic CDR2 and CDR2L antibodies affect Purkinje cell calcium homeostasis.

Paraneoplastic cerebellar degeneration (PCD) is characterized by loss of Purkinje cells (PCs) associated with progressive pancerebellar dysfunction in the presence of onconeural Yo antibodies. These antibodies recognize the cerebellar degeneration-related antigens CDR2 and CDR2L. Response to PCD therapy is disappointing due to limited understanding of the neuropathological mechanisms. Here, we report the pathological role of CDR antibodies on the calcium homeostasis in PCs. We developed an antibody-mediated PCD model based on co-incubation of cerebellar organotypic slice culture with human patient serum or rabbit CDR2 and CDR2L antibodies. The CDR antibody-induced pathology was investigated by high-resolution multiphoton imaging and biochemical analysis. Both human and rabbit CDR antibodies were rapidly internalized by PCs and led to reduced immunoreactivity of calbindin D28K (CB) and L7/Pcp-2 as well as reduced dendritic arborizations in the remaining PCs. Washout of the CDR antibodies partially recovered CB immunoreactivity, suggesting a transient structural change in CB calcium-binding site. We discovered that CDR2 and CB co-immunoprecipitate. Furthermore, the expression levels of voltage-gated calcium channel Cav2.1, protein kinase C gamma and calcium-dependent protease, calpain-2, were increased after CDR antibody internalization. Inhibition of these signaling pathways prevented or attenuated CDR antibody-induced CB and L7/Pcp-2 immunoreactivity loss, morphological changes and increased protein expression. These results signify that CDR antibody internalization causes dysregulation of cell calcium homeostasis. Hence, drugs that modulate these events may represent novel neuroprotective therapies that limit the damaging effects of CDR antibodies and prevent PC neurodegeneration.

Immunotherapies influence the influenza vaccination response in multiple sclerosis patients: an explorative study.

BACKGROUND: The immunogenicity of influenza vaccines in MS patients undergoing immunomodulatory treatment is not well studied. OBJECTIVES: This explorative study investigated the influence of immunomodulatory treatment on MS patients receiving pandemic H1N1 (swine flu) vaccination in 2009 and seasonal influenza vaccination in 2010. METHODS: We investigated the immune response to pandemic H1N1 vaccination among 113 MS patients and 216 controls during the pandemic of 2009. We also investigated the serological response to seasonal influenza vaccination (2010 - 2011 season) among 49 vaccinated and 62 non-vaccinated MS patients, versus 73 controls. We evaluated these vaccine responses by haemagglutination inhibition assay. RESULTS: MS patients receiving immunomodulatory treatment had reduced protection (27.4%), compared to controls (43.5%) (p = 0.006), after pandemic H1N1 vaccination (2009). The rates of protection were not influenced by interferon beta treatment (44.4% protected), but were reduced among patients receiving glatiramer acetate (21.6%), natalizumab (23.5%), and mitoxantrone (0.0%). A similar pattern emerged after MS patients received a seasonal influenza vaccination in 2010. CONCLUSIONS: These findings suggest that MS patients receiving immunomodulatory therapies other than interferon beta should be considered for a vaccine response analysis and perhaps be offered a second dose of the vaccine, in cases of insufficient protection.

Paraneoplastic Hu and CRMP5 antibodies are present in smokers without cancer or neurological disease.

BACKGROUND AND OBJECTIVE: We investigated if the paraneoplastic Hu and collapsin response mediator protein 5 (CRMP5) antibodies could be used as early markers for lung cancer in smokers with or without chronic obstructive pulmonary disease (COPD). METHODS: Hu and CRMP5 antibodies were measured by radioimmunoprecipitation assay (RIPA) in sera from 552 smokers; 379 with and 173 without COPD. Three hundred blood donors served as controls. The positive sera were also tested by indirect immunofluorescence and line blot with recombinant proteins. The 552 smokers were matched with data from the Cancer Registry of Norway, and the hospital medical records from the subjects positive for Hu and CRMP5 antibodies were reviewed. The mean follow-up time was 4.4 years (range 2.5-5.7 years). RESULTS: The RIPA showed that 5/379 (1.3%) smokers with COPD had Hu antibodies and 1/379 (0.3%) smokers with COPD had CRMP5 antibodies. Only the smoker with the highest RIPA index had Hu antibodies also detected by immunofluorescence and line blot. One of 173 (0.6%) smokers without COPD had Hu antibodies, but none had CRMP5 antibodies. None of the 300 controls had Hu antibodies, but 2/300 (0.7%) had CRMP5 antibodies. Hu antibodies remained positive for more than 5 years. No cancer or neurological disease was recorded in the Hu or CRMP5 positive patients. The total cancer frequency in the smokers with and without COPD was 70/552 (13%). CONCLUSIONS: Hu and CRMP5 antibodies were not associated with cancer or neurological disease in a large cohort of smokers and are therefore not always paraneoplastic.

Paraneoplastic cerebellar and brainstem disorders.

Paraneoplastic cerebellar and brainstem disorders are a heterogeneous group that requires prompt recognition and treatment to help prevent irreversible neurologic injury. Paraneoplastic cerebellar degeneration is best characterized by Yo antibodies in patients with breast or ovarian cancer. Tr (DNER) antibodies in patients with Hodgkin lymphoma can also present with a pure cerebellar syndrome and is one of the few paraneoplastic syndromes found with hematological malignancy. Opsoclonus-myoclonus-ataxia syndrome presents in both pediatric and adult patients with characteristic clinical findings. Other paraneoplastic brainstem syndromes are associated with Ma2 and Hu antibodies, which can cause widespread neurologic dysfunction. The differential for these disorders is broad and also includes pharmacological side effects, infection or postinfectious processes, and neurodegenerative diseases. Although these immune-mediated disorders have been known for many years, mechanisms of pathogenesis are still unclear, and optimal treatment has not been established.

Serum neurofilament light chain associates with symptom burden in Lyme neuroborreliosis patients: a longitudinal cohort study from Norway.

OBJECTIVES: Serum neurofilament light chain (sNfL), an indicator of neuronal damage, is increasingly recognized as a potential biomarker for disease activity in neurodegenerative disorders. In this study, we wanted to investigate sNfL as a prognostic marker in a large, well-defined population of 90 patients with Lyme neuroborreliosis (LNB). In addition, we sought to explore associations between symptoms and sNfL levels during the acute phase of LNB. MATERIALS AND METHODS: Patients diagnosed with definite or possible LNB were recruited from a double-blinded, placebo-controlled, multi-center trial, in which the participants were randomly assigned to 2 or 6 weeks of oral doxycycline treatment. The sNfL levels were measured using a single molecule array assay at both diagnosis and 6-month follow-up, and analysed against clinical parameters, variations in symptom burden and long-term complaints as assessed by a composite clinical score. RESULTS: At the time of diagnosis, approximately 60% of the patients had elevated sNfL levels adjusted for age. Notably, mean sNfL levels were significantly higher at diagnosis (52 pg/ml) compared to 6 months after treatment (12 pg/ml, p < 0.001), when sNfL levels had normalized in the majority of patients. Patients with objective signs of spinal radiculitis had significantly higher baseline sNfL levels compared to patients without spinal radiculitis (p = 0.033). CONCLUSION: Our findings suggest that sNfL can serve as a biomarker for peripheral nerve tissue involvement in the acute phase of LNB. As found in an earlier study, we confirm normalization of sNfL levels in blood after treatment. We found no prognostic value of acute-phase sNfL levels on patient outcome.

Mutations in ABHD12 cause the neurodegenerative disease PHARC: An inborn error of endocannabinoid metabolism.

Polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract (PHARC) is a neurodegenerative disease marked by early-onset cataract and hearing loss, retinitis pigmentosa, and involvement of both the central and peripheral nervous systems, including demyelinating sensorimotor polyneuropathy and cerebellar ataxia. Previously, we mapped this Refsum-like disorder to a 16 Mb region on chromosome 20. Here we report that mutations in the ABHD12 gene cause PHARC disease and we describe the clinical manifestations in a total of 19 patients from four different countries. The ABHD12 enzyme was recently shown to hydrolyze 2-arachidonoyl glycerol (2-AG), the main endocannabinoid lipid transmitter that acts on cannabinoid receptors CB1 and CB2. Our data therefore represent an example of an inherited disorder related to endocannabinoid metabolism. The endocannabinoid system is involved in a wide range of physiological processes including neurotransmission, mood, appetite, pain appreciation, addiction behavior, and inflammation, and several potential drugs targeting these pathways are in development for clinical applications. Our findings show that ABHD12 performs essential functions in both the central and peripheral nervous systems and the eye. Any future drug-mediated interference with this enzyme should consider the potential risk of long-term adverse effects.