Quantification of blood glial fibrillary acidic protein using a second-generation microfluidic assay. Validation and comparative analysis with two established assays.

OBJECTIVES: Increased levels of glial fibrillary acidic protein (GFAP) in blood have been identified as a valuable biomarker for some neurological disorders, such as Alzheimer's disease and multiple sclerosis. However, most blood GFAP quantifications so far were performed using the same bead-based assay, and to date a routine clinical application is lacking. METHODS: In this study, we validated a novel second-generation (2nd gen) Ella assay to quantify serum GFAP. Furthermore, we compared its performance with a bead-based single molecule array (Simoa) and a homemade GFAP assay in a clinical cohort of neurological diseases, including 210 patients. RESULTS: Validation experiments resulted in an intra-assay variation of 10 %, an inter-assay of 12 %, a limit of detection of 0.9 pg/mL, a lower limit of quantification of 2.8 pg/mL, and less than 20 % variation in serum samples exposed to up to five freeze-thaw cycles, 120 h at 4 °C and room temperature. Measurement of the clinical cohort using all assays revealed the same pattern of GFAP distribution in the different diagnostic groups. Moreover, we observed a strong correlation between the 2nd gen Ella and Simoa (r=0.91 (95 % CI: 0.88-0.93), p<0.0001) and the homemade immunoassay (r=0.77 (95 % CI: 0.70-0.82), p<0.0001). CONCLUSIONS: Our results demonstrate a high reliability, precision and reproducibility of the 2nd gen Ella assay. Although a higher assay sensitivity for Simoa was observed, the new microfluidic assay might have the potential to be used for GFAP analysis in daily clinical workups due to its robustness and ease of use.

Neurodegeneration or dysfunction in Phelan-McDermid syndrome? A multimodal approach with CSF and computational MRI.

BACKGROUND: Phelan-McDermid syndrome (PMS) is a rare multisystem disease with global developmental delay and autistic features. Genetically, the disease is based on a heterozygous deletion of chromosome 22q13.3 with involvement of at least part of the SHANK3 gene or heterozygous pathogenic variants in SHANK3. Pathophysiologically, this syndrome has been regarded as a synaptopathy, but current data suggest an additional concept, since axonal functions of neurons are also impaired, thus, the specific pathophysiological processes in this disease are not yet fully understood. Since symptoms of the autism spectrum, regression, and stagnation in development occur, we investigated whether neuroinflammatory and neurodegenerative processes may also play a role. To this end, we analysed biomarkers in cerebrospinal fluid (CSF) and parameters from magnetic resonance imaging with high-resolution structural T1w volumetry and diffusion tensor imaging analysis in 19 Phelan-McDermid syndrome patients. RESULTS: CSF showed no inflammation but abnormalities in tau protein and amyloid-ß concentrations, however, with no typical biomarker pattern as in Alzheimer's disease. It could be demonstrated that these CSF changes were correlated with integrity losses of the fibres in the corticospinal tract as well as in the splenium and dorsal part of the cingulum. High CSF levels of tau protein were associated with loss of integrity of fibres in the corticospinal tract; lower levels of amyloid-ß were associated with decreasing integrity of fibre tracts of the splenium and posterior cingulate gyrus. Volumetric investigations showed global atrophy of the white matter, but not the grey matter, and particularly not in temporal or mesiotemporal regions, as is typical in later stages of Alzheimer's disease. CONCLUSIONS: In summary, alterations of neurodegenerative CSF markers in PMS individuals could be demonstrated which were correlated with structural connectivity losses of the corticospinal tract, the splenium, and the dorsal part of the cingulum, which can also be associated with typical clinical symptoms in these patients. These findings might represent a state of dysfunctional processes with ongoing degenerative and regenerative processes or a kind of accelerated aging. This study should foster further clinical diagnostics like tau- and amyloid-PET imaging as well as novel scientific approaches especially in basic research for further mechanistic proof.

Shank3 related muscular hypotonia is accompanied by increased intracellular calcium concentrations and ion channel dysregulation in striated muscle tissue.

Phelan-McDermid syndrome (PMS) is a syndromic form of Autism Spectrum Disorders (ASD) classified as a rare genetic neurodevelopmental disorder featuring global developmental delay, absent or delayed speech, ASD-like behaviour and neonatal skeletal muscle hypotonia. PMS is caused by a heterozygous deletion of the distal end of chromosome 22q13.3 or SHANK3 mutations. We analyzed striated muscles of newborn Shank3Δ11(-/-) animals and found a significant enlargement of the sarcoplasmic reticulum as previously seen in adult Shank3Δ11(-/-) mice, indicative of a Shank3-dependent and not compensatory mechanism for this structural alteration. We analyzed transcriptional differences by RNA-sequencing of muscle tissue of neonatal Shank3Δ11(-/-) mice and compared those to Shank3(+/+) controls. We found significant differences in gene expression of ion channels crucial for muscle contraction and for molecules involved in calcium ion regulation. In addition, calcium storage- [i.e., Calsequestrin (CSQ)], calcium secretion- and calcium-related signaling-proteins were found to be affected. By immunostainings and Western blot analyses we could confirm these findings both in Shank3Δ11(-/-) mice and PMS patient muscle tissue. Moreover, alterations could be induced in vitro by the selective downregulation of Shank3 in C2C12 myotubes. Our results emphasize that SHANK3 levels directly or indirectly regulate calcium homeostasis in a cell autonomous manner that might contribute to muscular hypotonia especially seen in the newborn.

Guideline "Motor neuron diseases" of the German Society of Neurology (Deutsche Gesellschaft für Neurologie).

INTRODUCTION: In 2021, the Deutsche Gesellschaft für Neurology published a new guideline on diagnosis and therapy of motor neuron disorders. Motor neuron disorders affect upper motor neurons in the primary motor cortex and/or lower motor neurons in the brain stem and spinal cord. The most frequent motor neuron disease amyotrophic lateral sclerosis (ALS) is a rapidly progressive disease with an average life expectancy of 2-4 years with a yearly incidence of 3.1/100,000 in Central Europe (Rosenbohm et al. in J Neurol 264(4):749-757, 2017. https://doi.org/10.1007/s00415-017-8413-3 ). It is considered a rare disease mainly due to its low prevalence as a consequence of short disease duration. RECOMMENDATIONS: These guidelines comprise recommendations regarding differential diagnosis, neuroprotective therapies and multidisciplinary palliative care including management of respiration and nutrition as well as provision of assistive devices and end-of-life situations. CONCLUSION: Diagnostic and therapeutic guidelines are necessary due the comparatively high number of cases and the aggressive disease course. Given the low prevalence and the severe impairment of patients, it is often impossible to generate evidence-based data so that ALS guidelines are partially dependent on expert opinion.

CSF oligoclonal IgG bands are not associated with ALS progression and prognosis.

Introduction: Amyotrophic Lateral Sclerosis (ALS) is characterized by progressive motoneuron degeneration through cell autonomous and non-cell autonomous mechanisms; and the involvement of the innate and adaptive immune system has been hypothesized based on human and murine model data. We have explored if B-cell activation and IgG responses, as detected by IgG Oligoclonal bands (OCB) in serum and cerebrospinal fluid, were associated with ALS or with a subgroup of patients with distinct clinical features. Methods: IgG OCB were determined in patients affected by ALS (n=457), Alzheimer Disease (n=516), Mild Cognitive Impairment (n=91), Tension-type Headache (n=152) and idiopathic Facial Palsy (n=94). For ALS patients, clinico-demographic and survival data were prospectively collected in the Register Schabia. Results: The prevalence of IgG OCB is comparable in ALS and the four neurological cohorts. When the OCB pattern was considered (highlighting either intrathecal or systemic B-cells activation), no effect of OCB pattern on clinic-demographic parameters and overall. ALS patients with intrathecal IgG synthesis (type 2 and 3) were more likely to display infectious, inflammatory or systemic autoimmune conditions. Discussion: These data suggest that OCB are not related to ALS pathophysiology but rather are a finding possibly indicative a coincidental infectious or inflammatory comorbidity that merits further investigation.

Definition and clinical variability of SHANK3-related Phelan-McDermid syndrome.

Phelan-McDermid syndrome (PMS) is an infrequently described syndrome that presents with a disturbed development, neurological and psychiatric characteristics, and sometimes other comorbidities. As part of the development of European medical guidelines we studied the definition, phenotype, genotype-phenotype characteristics, and natural history of the syndrome. The number of confirmed diagnoses of PMS in different European countries was also assessed and it could be concluded that PMS is underdiagnosed. The incidence of PMS in European countries is estimated to be at least 1 in 30,000. Next generation sequencing, including analysis of copy number variations, as first tier in diagnostics of individuals with intellectual disability will likely yield a larger number of individuals with PMS than presently known. A definition of PMS by its phenotype is at the present not possible, and therefore PMS-SHANK3 related is defined by the presence of SHANK3 haploinsufficiency, either by a deletion involving region 22q13.2-33 or a pathogenic/likely pathogenic variant in SHANK3. In summarizing the phenotype, we subdivided it into that of individuals with a 22q13 deletion and that of those with a pathogenic/likely pathogenic SHANK3 variant. The phenotype of individuals with PMS is variable, depending in part on the deletion size or whether only a variant of SHANK3 is present. The core phenotype in the domains development, neurology, and senses are similar in those with deletions and SHANK3 variants, but individuals with a SHANK3 variant more often are reported to have behavioural disorders and less often urogenital malformations and lymphedema. The behavioural disorders may, however, be a less outstanding feature in individuals with deletions accompanied by more severe intellectual disability. Data available on the natural history are limited. Results of clinical trials using IGF-1, intranasal insulin, and oxytocin are available, other trials are in progress. The present guidelines for PMS aim at offering tools to caregivers and families to provide optimal care to individuals with PMS.

Consensus recommendations on Epilepsy in Phelan-McDermid syndrome.

Phelan-McDermid syndrome (PMS) is a 22q13.3 deletion syndrome that presents with a disturbed development, neurological and psychiatric characteristics, and sometimes other comorbidities like seizures. The epilepsy manifests itself in a variety of seizure semiologies. Further diagnostics using electroencephalogram (EEG) and brain magnetic resonance imaging (MRI) are important in conjunction with the clinical picture of the seizures to decide whether anticonvulsant therapy is necessary. As part of the development of European consensus guidelines we focussed on the prevalence and semiology of epileptic seizures in PMS associated with a pathogenic variant in the SHANK3 gene or the 22q13 deletion involving SHANK3, in order to then be able to make recommendations regarding diagnosis and therapy.

Increased Radiation Sensitivity in Patients with Phelan-McDermid Syndrome.

Phelan-McDermid syndrome is an inherited global developmental disorder commonly associated with autism spectrum disorder. Due to a significantly increased radiosensitivity, measured before the start of radiotherapy of a rhabdoid tumor in a child with Phelan-McDermid syndrome, the question arose whether other patients with this syndrome also have increased radiosensitivity. For this purpose, the radiation sensitivity of blood lymphocytes after irradiation with 2Gray was examined using the G0 three-color fluorescence in situ hybridization assay in a cohort of 20 patients with Phelan-McDermid syndrome from blood samples. The results were compared to healthy volunteers, breast cancer patients and rectal cancer patients. Independent of age and gender, all but two patients with Phelan-McDermid syndrome showed significantly increased radiosensitivity, with an average of 0.653 breaks per metaphase. These results correlated neither with the individual genetic findings nor with the individual clinical course, nor with the respective clinical severity of the disease. In our pilot study, we saw a significantly increased radiosensitivity in lymphocytes from patients with Phelan-McDermid syndrome, so pronounced that a dose reduction would be recommended if radiotherapy had to be performed. Ultimately, the question arises as to the interpretation of these data. There does not appear to be an increased risk of tumors in these patients, since tumors are rare overall. The question, therefore, arose as to whether our results could possibly be the basis for processes, such as aging/preaging, or, in this context, neurodegeneration. There are no data on this so far, but this issue should be pursued in further fundamentally based studies in order to better understand the pathophysiology of the syndrome.

Consensus recommendations on altered sensory functioning in Phelan-McDermid syndrome.

Altered sensory functioning is often observed in individuals with SHANK3 related Phelan-McDermid syndrome (PMS). Compared to typically developing individuals and individuals with an autism spectrum disorder, it has been suggested that there are distinctive features of sensory functioning in PMS. More hyporeactivity symptoms and less hyperreactivity and sensory seeking behaviour are seen, particularly in the auditory domain. Hypersensitivity to touch, possible overheating or turning red easily and reduced pain response are often seen. In this paper the current literature on sensory functioning in PMS is reviewed and recommendations for caregivers, based on consensus within the European PMS consortium, are given.

Phelan McDermid Syndrome: Multiple Sclerosis as a Rare but Treatable Cause for Regression-A Case Report.

Phelan McDermid syndrome (PMcD) is a neurogenetic disease associated with haploinsufficiency of the SHANK3 gene due to a spectrum of anomalies in the terminal region of the long arm of chromosome 22. SHANK3 is the abbreviation for SH3 domain and ankyrin repeat-containing protein, a gene that encodes for proteins of the postsynaptic density (PSD) of excitatory synapses. This PSD is relevant for the induction and plasticity of spine and synapse formation as a basis for learning processes and long-term potentiation. Individuals with PMcD present with intellectual disability, muscular hypotonia, and severely delayed or absent speech. Further neuropsychiatric manifestations cover symptoms of the autism spectrum, epilepsy, bipolar disorders, schizophrenia, and regression. Regression is one of the most feared syndromes by relatives of PMcD patients. Current scientific evidence indicates that the onset of regression is variable and affects language, motor skills, activities of daily living and cognition. In the case of regression, patients normally undergo further diagnostics to exclude treatable reasons such as complex-focal seizures or psychiatric comorbidities. Here, we report, for the first time, the case of a young female who developed progressive symptoms of regression and a dystonic-spastic hemiparesis that could be traced back to a comorbid multiple sclerosis and that improved after treatment with methylprednisolone.

Haemodynamics and cerebral oxygenation of neonatal piglets in the immediate ex utero period supported by mechanical ventilation or ex utero oxygenator.

KEY POINTS: The margin of human viability has extended to the extremes of gestational age (<24 weeks) when the lungs are immature and ventilator-induced lung injury is common. Artificial placenta technology aims to extend gestation ex utero in order to allow the lungs additional time to develop prior to entering an air-breathing environment. We compared the haemodynamics and cerebral oxygenation of piglets in the immediate period post-oxygenator (OXY) transition against both paired in utero measures and uniquely against piglets transitioned onto mechanical ventilation (VENT). Post-transition, OXY piglets became hypotensive with reduced carotid blood flow in comparison with both paired in utero measures and VENT piglets. The addition of a pump to the oxygenator circuit may be required to ensure haemodynamic stability in the immediate post-transition period. ABSTRACT: Gestational age at birth is a major predictor of wellbeing; the lower the gestational age, the greater the risk of mortality and morbidity. At the margins of human viability (<24 weeks gestation) immature lungs combined with the need for early ventilatory support means lung injury and respiratory morbidity is common. The abrupt haemodynamic changes consequent on birth may also contribute to preterm-associated brain injury, including intraventricular haemorrhage. Artificial placenta technology aims to support oxygenation, haemodynamic stability and ongoing fetal development ex utero until mature enough to safely transition to a true ex utero environment. We aimed to characterize the impact of birth transition onto either an oxygenator circuit or positive pressure ventilation on haemodynamic and cerebral oxygenation of the neonatal piglet. At 112 days gestation (term = 115 days), fetal pigs underwent instrumentation surgery and transitioned onto either an oxygenator (OXY, n = 5) or ventilatory support (VENT, n = 8). Blood pressure (BP), carotid blood flow and cerebral oxygenation in VENT piglets rose from in utero levels to be significantly higher than OXY piglets post-transition. OXY piglet BP, carotid blood flow and carotid oxygen delivery (DO2 ) decreased from in utero levels post-transition; however, cerebral regional oxygen saturation (rSO2 ) was maintained at fetal-like levels. OXY piglets became hypoxaemic and retained CO2 . Whether OXY piglets are able to maintain cerebral rSO2 under these conditions for a prolonged period is yet to be determined. Improvements to OXY piglet oxygenation may lie in maintaining piglet BP at in utero levels and enhancing oxygenator circuit flow.

Tick-Borne Encephalitis: A Differential Pattern of Intrathecal Humoral Immune Response and Inflammatory Cell Composition Compared with Other Viral CNS Infections.

To investigate whether and how cerebrospinal fluid (CSF) findings can contribute to distinguish tick-borne encephalitis (TBE) from herpes simplex virus (HSV) and varicella zoster virus (VZV) induced central nervous system (CNS) infections (HSV-I, VZV-I). Chart review and identification of TBE, HSV- I, and VZV-I was carried out, fulfilling the following criteria: (1) clinical signs of encephalitis and/or meningitis, (2) complete CSF analysis and confirmed viral etiology by either PCR or antibody testing in CSF, (3) hospitalized patients, and (4) available brain magnetic resonance imaging (MRI). Fifty-nine patients with 118 CSF/serum pairs were included. These comprised 21 with TBE (35 CSF/serum pairs), 20 (40 CSF/serum pairs) with HSV-I, and 18 (43 CSF/serum pairs) with VZV-I. In contrast to HSV-I and VZV-I, CSF cell differentiation in TBE showed more often an increased (>20%) proportion of granulocytes (p < 0.01) and a more frequent quantitative intrathecal IgM synthesis (p = 0.001 and p < 0.01, respectively), while the second was even more pronounced when follow-up CSF analyses were included (p < 0.001). CSF findings help to distinguish TBE from other viral infections. In cases with CSF pleocytosis and a positive history for a stay in or near an endemic area, TBE antibodies in CSF and serum should be determined, especially if granulocytes in CSF cell differentiation and/or an intrathecal IgM synthesis is present.

Autism-associated SHANK3 mutations impair maturation of neuromuscular junctions and striated muscles.

Heterozygous mutations of the gene encoding the postsynaptic protein SHANK3 are associated with syndromic forms of autism spectrum disorders (ASDs). One of the earliest clinical symptoms in SHANK3-associated ASD is neonatal skeletal muscle hypotonia. This symptom can be critical for the early diagnosis of affected children; however, the mechanism mediating hypotonia in ASD is not completely understood. Here, we used a combination of patient-derived human induced pluripotent stem cells (hiPSCs), Shank3Δ11(-/-) mice, and Phelan-McDermid syndrome (PMDS) muscle biopsies from patients of different ages to analyze the role of SHANK3 on motor unit development. Our results suggest that the hypotonia in SHANK3 deficiency might be caused by dysfunctions in all elements of the voluntary motor system: motoneurons, neuromuscular junctions (NMJs), and striated muscles. We found that SHANK3 localizes in Z-discs in the skeletal muscle sarcomere and co-immunoprecipitates with α-ACTININ. SHANK3 deficiency lead to shortened Z-discs and severe impairment of acetylcholine receptor clustering in hiPSC-derived myotubes and in muscle from Shank3Δ11(-/-) mice and patients with PMDS, indicating a crucial role for SHANK3 in the maturation of NMJs and striated muscle. Functional motor defects in Shank3Δ11(-/-) mice could be rescued with the troponin activator Tirasemtiv that sensitizes muscle fibers to calcium. Our observations give insight into the function of SHANK3 besides the central nervous system and imply potential treatment strategies for SHANK3-associated ASD.

Severe white matter damage in SHANK3 deficiency: a human and translational study.

OBJECTIVE: Heterozygous SHANK3 mutations or partial deletions of the long arm of chromosome 22, also known as Phelan-McDermid syndrome, result in a syndromic form of the autism spectrum as well as in global developmental delay, intellectual disability, and several neuropsychiatric comorbidities. The exact pathophysiological mechanisms underlying the disease are still far from being deciphered but studies of SHANK3 models have contributed to the understanding of how the loss of the synaptic protein SHANK3 affects neuronal function. METHODS AND RESULTS: Diffusion tensor imaging-based and automatic volumetric brain mapping were performed in 12 SHANK3-deficient participants (mean age 19 ± 15 years) versus 14 age- and gender-matched controls (mean age 29 ± 5 years). Using whole brain-based spatial statistics, we observed a highly significant pattern of white matter alterations in participants with SHANK3 mutations with focus on the long association fiber tracts, particularly the uncinate tract and the inferior fronto-occipital fasciculus. In contrast, only subtle gray matter volumetric abnormalities were detectable. In a back-translational approach, we observed similar white matter alterations in heterozygous isoform-specific Shank3 knockout (KO) mice. Here, in the baseline data sets, the comparison of Shank3 heterozygous KO vs wildtype showed significant fractional anisotropy reduction of the long fiber tract systems in the KO model. The multiparametric Magnetic Resonance Imaging (MRI) analysis by DTI and volumetry demonstrated a pathology pattern with severe white matter alterations and only subtle gray matter changes in the animal model. INTERPRETATION: In summary, these translational data provide strong evidence that the SHANK3-deficiency-associated pathomechanism presents predominantly with a white matter disease. Further studies should concentrate on the role of SHANK3 during early axonal pathfinding/wiring and in myelin formation.

Differential diagnosis of peripheral facial nerve palsy: a retrospective clinical, MRI and CSF-based study.

BACKGROUND: Facial nerve palsy is the most common cranial nerve disorder. There is no consensus on a single diagnostic tool deemed as the 'gold standard' for distinguishing between idiopathic (Bell's palsy) and symptomatic causes. The diagnosis is one of exclusion and most often made on physical examination. In the present study, we describe the etiological background of peripheral facial palsy in N = 509 patients and evaluate the relevance of cerebrospinal fluid (CSF) analysis and magnetic resonance imaging (MRI) in differential diagnosis. METHODS: We carried out a retrospective data analysis of 509 patients with the clinical diagnosis of peripheral facial palsy admitted to our emergency unit between January 2006 and January 2017. All patients were seen clinically; their CSF was analyzed and MRI was performed. RESULTS: Of N = 526 patients with isolated facial palsy, 17 patients were excluded because they did not consent to CSF analysis. Of the remaining N = 509 patients, 383 patients (75.2%) were diagnosed with idiopathic facial palsy. In the remaining 126 patients (24.8%), the following etiologies for facial palsy could be found: Ramsay-Hunt-Syndrome (N = 34), Lyme Neuroborreliosis (N = 32), other viral/bacterial central nervous system (CNS) infections (N = 8), neoplasias (N = 18), autoimmune disease (N = 12), otogenous processes (N = 6), or other etiologies (N = 16). Analysis of the CSF showed 85% sensitivity for Ramsay-Hunt-Syndrome and 100% for Lyme Neuroborreliosis and other viral/bacterial CNS infections. CSF analysis proved a reliable diagnostic tool for identifying these subgroups. MRI with contrast compounds, as performed in 409 patients, was the most important tool in diagnosing neoplasias (88% sensitivity) and otogenous processes (83% sensitivity). MRI with contrast-enhancing compounds did not reveal additional information concerning inflammatory facial nerve lesions when performed the same day as hospital admission. CONCLUSIONS: Although peripheral facial palsy was predominantly idiopathic (75.3%) in our cohort, the disease was caused in approximately 25% of the patients by factors which require specific treatment. In the present study, CSF analysis proved to be the leading method for the diagnosis of Ramsay-Hunt-Syndrome, Lyme Neuroborreliosis, and other CNS infections. These subgroups made up approximately 15% of our cohort. To detect these subgroups reliably, routine use of CSF analysis in peripheral facial palsy may be advisable, whereas MRI proved to be useful for exclusion of otogenic and neoplastic processes with a sensitivity of 83% and 88%. We found that the use of MRI with contrast-enhancing compounds does not provide additional diagnostic information on the day of hospital admission. Hence, the potential benefits of routine use of MRI in patients with facial nerve palsy should be weighed against health care cost factors.

Ribosomal transcription is regulated by PGC-1alpha and disturbed in Huntington's disease.

PGC-1α is a versatile inducer of mitochondrial biogenesis and responsive to the changing energy demands of the cell. As mitochondrial ATP production requires proteins that derive from translation products of cytosolic ribosomes, we asked whether PGC-1α directly takes part in ribosomal biogenesis. Here, we show that a fraction of cellular PGC-1α localizes to the nucleolus, the site of ribosomal transcription by RNA polymerase I. Upon activation PGC-1α associates with the ribosomal DNA and boosts recruitment of RNA polymerase I and UBF to the rDNA promoter. This induces RNA polymerase I transcription under different stress conditions in cell culture and mouse models as well as in healthy humans and is impaired already in early stages of human Huntington's disease. This novel molecular link between ribosomal and mitochondrial biogenesis helps to explain sarcopenia and cachexia in diseases of neurodegenerative origin.