Case Report: Primary Diffuse Leptomeningeal Oligodendrogliomatosis in a Young Adult Cat

A 2-year-old cat was presented with progressive ataxia. Despite treatment the animal died. Pathomorphological examination revealed a widespread leptomeningeal mass at all levels of the central nervous system accentuated on the cervical spinal cord and the medulla oblongata without presence of a primary intraaxial tumor. The neoplasm was mainly composed of round, uninucleate cells with hyperchromatic nuclei, which were immunopositive for OLIG2, doublecortin, MAP2, synaptophysin, and vimentin, indicating components of both oligodendroglial and neuronal differentiation. Ki-67 immunohistochemistry indicated a high proliferation activity of the neoplasm. Few GFAP positive and Iba-1 positive cells were interpreted as reactive astrocytes and macrophages or microglia, respectively. The tumor was immunonegative for CD3, CD20, PAX5, MUM1, pan-cytokeratin, S100, NSE, p75NTR, NeuN and periaxin. These findings led to the diagnosis of primary diffuse leptomeningeal oligodendrogliomatosis. This is the first reported case of this entity in a young cat, which should be considered as a differential diagnosis for diffuse subarachnoidal round cell infiltrates.

LINE-1 activation in the cerebellum drives ataxia

ABSTRACTPrevious studies have revealed that dysregulation of long interspersed nuclear element 1 (LINE-1), a dominant class of transposable elements in the human genome, correlates with neurodegeneration1–3. Yet whether LINE-1 dysregulation is causal to disease pathogenesis has not been proven directly. Here, we demonstrate that expression of evolutionarily younger LINE-1 families is elevated in the cerebella of ataxia telangiectasia (AT) patients, which was correlated with extensive downregulation of epigenetic silencers. To examine whether LINE-1 activation causes neurologic disease, we established an approach to directly target and activate the promoter of a young family of LINE-1 in mice. LINE-1 activation in the cerebellum was sufficient to lead to robust progressive ataxia. Purkinje cells in the diseased mice exhibited marked electrophysiological dysfunctions and degeneration with a significant accumulation of cytoplasmic ribonucleoprotein LINE-1Orf1p aggregates, endoplasmic reticulum (ER) stress, and DNA damage. Treatment with lamivudine, a nucleoside reverse transcriptase inhibitor, blunted the disease progression by reducing DNA damage, attenuating gliosis and interferon gene signature, and recovering the loss of key functional molecules for calcium homeostasis in Purkinje cells. This study provides direct evidence that young LINE-1 activation drives ataxia phenotype, and points to its pleiotropic effects leading to DNA damage, inflammation, and dysfunction and degeneration of neurons.

Progressive Myoclonus Epilepsies

Background and ObjectivesTo assess the current diagnostic yield of genetic testing for the progressive myoclonus epilepsies (PMEs) of an Italian series described in 2014 where Unverricht-Lundborg and Lafora diseases accounted for ∼50% of the cohort.MethodsOf 47/165 unrelated patients with PME of indeterminate genetic origin, 38 underwent new molecular evaluations. Various next-generation sequencing (NGS) techniques were applied including gene panel analysis (n = 7) and/or whole-exome sequencing (WES) (WES singleton n = 29, WES trio n = 7, and WES sibling n = 4). In 1 family, homozygosity mapping was followed by targeted NGS. Clinically, the patients were grouped in 4 phenotypic categories: “Unverricht-Lundborg disease-like PME,” “late-onset PME,” “PME plus developmental delay,” and “PME plus dementia.”ResultsSixteen of 38 (42%) unrelated patients reached a positive diagnosis, increasing the overall proportion of solved families in the total series from 72% to 82%. Likely pathogenic variants were identified in NEU1 (2 families), CERS1 (1 family), and in 13 nonfamilial patients in KCNC1 (3), DHDDS (3), SACS, CACNA2D2, STUB1, AFG3L2, CLN6, NAXE, and CHD2. Across the different phenotypic categories, the diagnostic rate was similar, and the same gene could be found in different phenotypic categories.DiscussionThe application of NGS technology to unsolved patients with PME has revealed a collection of very rare genetic causes. Pathogenic variants were detected in both established PME genes and in genes not previously associated with PME, but with progressive ataxia or with developmental encephalopathies. With a diagnostic yield >80%, PME is one of the best genetically defined epilepsy syndromes.

Polyglutamine Ataxias: Our Current Molecular Understanding and What the Future Holds for Antisense Therapies

Polyglutamine (polyQ) ataxias are a heterogenous group of neurological disorders all caused by an expanded CAG trinucleotide repeat located in the coding region of each unique causative gene. To date, polyQ ataxias encompass six disorders: spinocerebellar ataxia types 1, 2, 3, 6, 7, and 17 and account for a larger group of disorders simply known as polyglutamine disorders, which also includes Huntington’s disease. These diseases are typically characterised by progressive ataxia, speech and swallowing difficulties, lack of coordination and gait, and are unfortunately fatal in nature, with the exception of SCA6. All the polyQ spinocerebellar ataxias have a hallmark feature of neuronal aggregations and share many common pathogenic mechanisms, such as mitochondrial dysfunction, impaired proteasomal function, and autophagy impairment. Currently, therapeutic options are limited, with no available treatments that slow or halt disease progression. Here, we discuss the common molecular and clinical presentations of polyQ spinocerebellar ataxias. We will also discuss the promising antisense oligonucleotide therapeutics being developed as treatments for these devastating diseases. With recent advancements and therapeutic approvals of various antisense therapies, it is envisioned that some of the studies reviewed may progress into clinical trials and beyond.

A Novel ATM Gene Mutation Affecting Splicing in an Ataxia-Telangiectasia Patient

Ataxia-telangiectasia (AT) is an autosomal recessive disorder characterized by progressive ataxia, choreoathetosis and immunodeficiency beginning in early childhood. An 8-year-old girl was referred with a diagnosis of AT. She had gait disturbance and dysarthria for 3years. Multiple cutaneous telangiectases were observed on her face, trunk and limbs. Sequence analysis of the <i>ATM</i> gene revealed a homozygous c.7308–15A&#x3e;G mutation in IVS49. Human Splicing Finder predicted that the mutation could activate an intronic cryptic acceptor site. We designed primers for amplification of related exons (48–50) from cDNA for evaluating splicing pattern. Sequencing of <i>ATM</i> exons 48–50 revealed a 14-nucleotide insertion from intron 49, between exons 49 and 50, resulting in premature termination of translation at codon 2439. To conclude, we report a novel mutation in a classical AT case, which resulted in an alternatively spliced transcript and was predicted to form a truncated protein or null protein due to nonsense-mediated decay.

Autoimmune glial fibrillary acidic protein astrocytopathy presented as ataxia, myoclonus and bulbar syndrome: a case report and review of the literature

ObjectiveTo describe an atypical case of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy.ResultsA patient in his 60s presented with 6 months of progressive ataxia, proximal myoclonus and bulbar symptomatology. Cerebrospinal fluid (CSF) analysis showed monocytic pleocytosis, elevated protein level and elevated adenosine deaminase (ADA) level. CSF microbiological studies were negative and brain and cervical MRI showed no significant findings. We tested for nuclear, cytoplasmatic and synaptic neural autoantibodies as well as anti-GFAP antibodies. While awaiting these results, the patient was commenced on methylprednisolone boluses (1 g/day for 5 days), noting rapid neurological improvement. Eventually, CSF tests were positive for anti-GFAP antibodies.ConclusionWe report atypical manifestations of GFAP astrocytopathy. Further research is needed to fully understand the spectrum of neurological manifestations of this autoimmune disease and facilitate timely diagnosis.

Stiff-Eye Syndrome—Anti-GAD Ataxia Presenting with Isolated Ophthalmoplegia: A Case Report

Anti-GAD ataxia is one of the most common forms of immune-mediated cerebellar ataxias. Many neurological syndromes have been reported in association with anti-GAD. Ophthalmoparesis has been described in stiff person syndrome. We report a case of anti-GAD ataxia presenting initially with isolated ophthalmoplegia and showing complete resolution after immunotherapy. A 26-year-old male patient presented with ophthalmoparesis characterized by tonic upwards deviation of the right eye. In the following month, he developed progressive ataxia with anti-GAD titers of 1972 UI/mL. After treatment with methylprednisolone and immunoglobulin, there was complete resolution of symptoms and anti-GAD titers decreased. This is the first report of isolated ophthalmoparesis due to tonic eye deviation associated with anti-GAD antibodies without stiff-person syndrome. Tonic eye deviation has been reported in SPS, possibly secondary to continuous discharge in gaze holding neurons in the brainstem (similar to what occurs in spinal motor neurons). With growing evidence for ocular abnormalitites in SPS, anti-GAD associated neurological syndromes should be included in the differential diagnosis of isolated ophthalmoplegia.