CNTNAP2 Research Articles

Immunotherapy-Resistant Neuropathic Pain and Fatigue Predict Quality-of-Life in Contactin-Associated Protein-Like 2 Antibody Disease.

The long-term clinical outcomes and associated prognostic factors in contactin-associated protein-like 2 (CASPR2)-antibody diseases are unknown. A total of 75 participants with CASPR2 antibodies were longitudinally assessed for disability, quality-of-life, and chronic pain. Although most symptoms improved within 6 months of treatment, neuropathic pain and fatigue were the most immunotherapy refractory, and persisted for up to 6 years. Furthermore, these two factors-but not CASPR2 antibody levels or subclasses-independently predicted worse disability and quality-of-life at 24 months. Quality-of-life varied widely for any given modified Rankin Scale score, indicating a divergence between patient and clinician assessed outcomes. Further work should study the relative importance of these measures, and the immunopathogenesis underlying intractable symptoms. ANN NEUROL 2025.

Low Plasma Levels of Contactin-Associated Protein-Like 2 in Children with Autism Spectrum Disorder: Links to Neural Development.

Autism spectrum disorder (ASD) is a condition of atypical neurodevelopment and is characterized by social communication problems and repetitive patterns of behavior. Early diagnosis and intervention are decisive for managing symptoms and improving outcomes. Contactin-associated protein-like 2 (CNTNAP2) protein is implicated in neural development and plays a role in brain connectivity and synapse formation. Genetic research has shown a possible link between CNTNAP2 and ASD. We aimed to discover the blood plasma levels of CNTNAP2 in children with ASD and explore the potential association between CNTNAP2 concentrations and ASD severity. This case-control study included children with ASD (n=40) and aged-matched healthy controls (n=40). Blood plasma levels of CNTNAP2 were measured using enzyme-linked immunosorbent assay (ELISA). The Children Autism Rating Scale (CARS) and Social Responsiveness Scale (SRS) were used to assess the severity of the ASD. Spearman correlation coefficient (r) was used to correlate the variables. Children with severe ASD had significantly lower CNTNAP2 levels (0.31 (0.14) ng/mL, p=0.003) compared to normal controls (0.47 (0.24) ng/mL). However, CNTNAP2 levels of children with mild autism (0.44(0.22), ng/mL, p=0.77) were not significantly different as compared to normal controls (0.47 (0.24) ng/mL). Furthermore, a significant difference was found between CNTNAP2 levels, by comparing themild and severe groups based on theCARS (p= 0.05). Furthermore, no significant correlation between CNTNAP2 levels, and severity scores (CARS and SRS), was obtained. However, a significant correlation between CNTNAP2 and age was observed. The low CNTNAP2 plasma level in children with ASD indicated that it might be involved in the pathophysiology of ASD. Nevertheless, these results should be interpreted with care till more studies are achieved using a larger population to decide whether the reduction in CNTNAP2 plasma level is a mere outcome of ASD or it plays a pathogenic role in the disease.

CASPR2-related epilepsy: A distinctive and unrecognized form of epilepsy in adult and elderly males.

The aim of this study was to describe the clinical features of contactin-associated protein-like 2 (CASPR2)-IgG-associated seizures. Nine patients were retrospectively collected from two epilepsy centers. For each patient we obtained a full clinical, neurophysiological, and MRI study along with detection of antineuronal autoantibodies from serum and CSF. The patients were followed up for 1-6 years. The patients were nine male subjects aged 56-85 years (mean: 66) with a 1- to 14-year (mean: 6,3 median: 6) history of seizures. The seizures were classified as focal onset seizures with impaired awareness, usually preceded by epigastric aura (two), piloerection (two), olfactory hallucinations (two), nausea and dizziness (one). Tonic-clonic seizures were present in five patients. Seizure frequency was high in six cases and sporadic in three. Most patients reported memory impairment (eight) or behavioral/mood changes (four). Interictal EEGs usually showed bilateral or unilateral temporal epileptiform abnormalities. A number of seizures arising from the temporal lobes, with bilateral asynchronous onset, were recorded on long-term video-EEG monitoring in two patients. MRI disclosed nonspecific white matter T2 hyperintensities suggestive of chronic vascular changes in four patients and bilateral T2-FLAIR amygdalo-hippocampal hyperintensity in three cases. Neuropsychological study demonstrated various degrees of cognitive impairment in the majority of cases. Increased titers of CASPR2 autoantibodies were detected in the serum and CSF, which persisted over time in four cases. Drug resistance to common anti-seizure medications was present in seven cases who benefited from immunotherapy. CASPR2-IgG testing should be performed among old male patients with a recent or even not recent onset of focal seizures with impaired awareness particularly when these seizures are accompanied by cognitive impairment or behavioral disturbances. In these cases, anti-seizure medications may be ineffective while immunotherapy may lead to a prompt improvement of seizures and cognitive deficits.

Investigating Sequence Variations in CNTNAP2 and SETBP1 Genes in Language Disorders.

Language disorder, a prevalent developmental disorder, impedes children's communication skills, with genetic and environmental factors playing pivotal roles in its pathomechanism. This study aims to investigate the involvement of sequence variations in SETBP1 and CNTNAP2 genes, along with environmental variables, in language disorder's etiology. Between September 2022 and March 2023, thirty children aged 2-7 diagnosed with language disorders according to DSM-5 criteria, and evaluated using the Ankara Developmental Screening Inventory, were studied to identify genetic and environmental factors contributing to etiology.Thirty healthy children with similar age were included as a control group. DNA samples isolated from peripheral blood of both groups were analyzed for SETBP1 and CNTNAP2 genes using next-generation sequencing (custom design panel). The frequencies and clinical significance of the identified variants was evaluated, and variant verification and segregation analyses were performed by Sanger sequencing. The obtained data were compared using appropriate statistical methods. Language disorder showed a male-dominant distribution. The SETBP1 rs11082414-CC genotype frequency was significantly higher in patients (p = 0.024), and two rare variants (CNTNAP2: c.973C>G:p.P325A; CNTNAP2: c.2236 G>A:p.D746N) were exclusive to cases. In silico analyses yielded conflicting results for rare variants, inherited paternally from unaffected parents. Among non-genetic factors, patients had higher birth weights (p = 0.043) and shorter lactation durations (p = 0.044). Homozygosity for SETBP1 rs11082414 polymorphic variant increases language disorder susceptibility. This study underscores the genetic dimension of language disorder, urging physicians' awareness and early intervention strategies to mitigate its impact.

C9orf72 Gene-Associated Frontotemporal Dementia Mimicking Autoimmune Pathology.

The C9orf72 mutation can manifest in diverse clinical ways, including rapid cognitive decline, parkinsonism, or late-life neuropsychiatric symptoms, sometimes mimicking autoimmune encephalitis. A 64-year-old female presented to the autoimmune neurology clinic with rapidly progressive dementia (RPD) associated with episodes of headache, confusion, auditory hallucinations, and abnormal electroencephalogram. She was treated empirically at an outside hospital for possible autoimmune encephalitis with intravenous methylprednisolone, but there was no improvement, and rapid cognitive decline continued. Family history was notable for RPD with akinetic mutism in her sister, sudden severe depression followed by parkinsonism with progressive dementia in her father in his 60s, and late-life gradually progressive dementia in her mother. Additional testing revealed a low titer positive contactin-associated protein-like 2 (CASPR2) immunoglobulin G (IgG) in the serum and elevated CSF 14-3-3 protein. CSF CASPR2 IgG and real-time quaking-induced conversion for Creutzfeldt-Jakob disease were negative. Brain MRI showed normal parenchymal volume. Genetic testing was conducted, which identified a heterozygous pathogenic hexanucleotide tandem repeat expansion in the C9orf72 gene. This case underscores the phenotypic variability of C9orf72 mutation and the importance of a detailed family history exploring young or atypical deaths and neuropsychiatric symptoms or behavioral changes. Genetic etiologies are crucial to consider in those with a family history concerning autosomal dominant inheritance patterns of early-onset dementia, parkinsonism, or late-onset psychiatric disease. Emphasis is placed on considering alternative etiologies early, particularly when there is no response to first-line immunomodulation for suspected autoimmune dementia.

Uncommon Pediatric Immune-Mediated Epilepsy: Disease Course, Diagnosis, and Outcome - A Series of Three Cases.

Immune-mediated epilepsy (IME) constitutes a substantial proportion of drug-refractory epilepsies. Rapid diagnosis and prompt immunosuppression are required along with antiseizure medications (ASMs). Here we report three unrelated children who presented with fever, encephalopathy, and refractory epilepsy and subsequently tested positive for rare intraneuronal and surface receptor antibodies, namely, contactin-associated protein like 2 (CASPR2), glutamic acid decarboxylase (GAD65), and paraneoplastic antigen Ma2 (PNMA2). In all of them, brain magnetic resonance imaging (MRI) was noncontributory. Electroencephalography showed nonspecific interictal epileptic discharges. F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) brain scan revealed abnormality in metabolic pattern with hypermetabolism in basal ganglia, thalami, frontotemporal cortices, and cerebellar hemispheres, consistent with autoimmune encephalitis. Immunosuppression was initiated along with ASMs. Complete seizure freedom was achieved in GAD65 antibody IME and >50% seizure reduction in CASPR2 and PNMA2 antibody IME. A variable degree of behavioral problems persisted in all. Early immunosuppression is warranted in IME, but does not universally guarantee a complete response.

Isaacs' syndrome: Clinical and paraclinical perspectives in a series of cases.

Background: Isaacs' syndrome is a form of generalized peripheral nerve hyperexcitability (PNH) causing increased and continuous muscle activity characterized by muscle twitching, stiffness, cramps, myokymia, and pseudomyotonia. Herein, we aimed to review the clinical and paraclinical aspects of Isaacs' syndrome in a number of cases. Methods: We reported a series of 12 patients with Isaacs' syndrome, including their clinical features, electrophysiological findings, laboratory parameters, malignancy work-up, and therapeutic management. Results: In all cases, clinical and electrodiagnostic assessment was suggestive of Isaacs' syndrome. Of the 12 studied cases, 5 patients were positive for both leucine-rich glioma inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies, 5 patients were CASPR2 positive and LGI1 negative, and 1 had borderline positive titers for CASPR2 with negative LGI1 antibody. The search for underlying malignancies was inconclusive in all subjects. After symptomatic treatment, mostly with carbamazepine or gabapentin, immunotherapies with double filtration plasmapheresis or Intravenous immunoglobulin (IVIG) provided favorable outcomes. Ultimately, all subjects fully recovered after 3-6 months of follow-up and all signs and symptoms resolved. Conclusion: Despite the rarity of the disease, our results provide valuable information for understanding the epidemiological, clinical, and paraclinical features of Isaacs' syndrome.

Palatable solution overconsumption in the Cntnap2-/- murine model of autism: a link with oxytocin.

Dysregulated appetite is common in autism spectrum disorder (ASD) and it includes excessive interest in tasty foods. Overconsumption of palatable fluids has been found in the valproic acid-induced ASD rat. Though ASD has a strong genetic component, the link between ASD-related genes and appetite for palatable foods remains elusive. We focused on the CNTNAP2 gene whose deletion in mice recapitulates human ASD symptoms. We investigated whether Cntnap2-/- male mice consume greater amounts of palatable 10% sucrose, 0.1% saccharin, and 4.1% intralipid solutions offered in episodic meals either in a no-choice paradigm or a two-bottle choice test. We examined how sucrose intake affects c-Fos immunoreactivity in feeding-related brain areas. Finally, we determined doses at which intraperitoneal oxytocin decreases sucrose intake in mutants. In the single-bottle tests, Cntnap2-/- mice drank more sucrose, saccharin, and intralipid compared to WTs. Given a choice between two tastants, Cntnap2-/- mice had a higher preference for sucrose than intralipid. While the standard 1 mg/kg oxytocin dose reduced sucrose intake in WTs, a low oxytocin dose (0.1 mg/kg) decreased sucrose intake in Cntnap2-/- mice. Sucrose intake induced a more robust c-Fos response in wild-type (WT) than Cntnap2-/- mice in the reward and hypothalamic sites and it increased the percentage of Fos-immunoreactivity oxytocin neurons in WTs, but not in mutants. We conclude that Cntnap2-/- mice overconsume palatable solutions, especially sucrose, beyond levels seen in WTs. This excessive consumption is associated with blunted c-Fos immunoreactivity in feeding-related brain sites, and it can be reversed by low-dose oxytocin.

Autoimmune Encephalitis.

This article focuses on the clinical features and diagnostic evaluations that accurately identify patients with ever-expanding forms of antibody-defined encephalitis. Forms of autoimmune encephalitis are more prevalent than infectious encephalitis and represent treatable neurologic syndromes for which early immunotherapies lead to the best outcomes. A clinically driven approach to identifying many autoimmune encephalitis syndromes is feasible, given the typically distinctive features associated with each antibody. Patient demographics alongside the presence and nature of seizures, cognitive impairment, psychiatric disturbances, movement disorders, and peripheral features provide a valuable set of clinical tools to guide the detection and interpretation of highly specific antibodies. In turn, these clinical features in combination with serologic findings and selective paraclinical testing, direct the rationale for the administration of immunotherapies. Observational studies provide the mainstay of evidence guiding first- and second-line immunotherapy administration in autoimmune encephalitis and, whereas these typically result in some clinical improvements, almost all patients have residual neuropsychiatric deficits, and many experience clinical relapses. An improved pathophysiologic understanding and ongoing clinical trials can help to address these unmet medical needs. Antibodies against central nervous system proteins characterize various autoimmune encephalitis syndromes. The most common targets include leucine-rich glioma inactivated protein 1 (LGI1), N-methyl-d-aspartate (NMDA) receptors, contactin-associated proteinlike 2 (CASPR2), and glutamic acid decarboxylase 65 (GAD65). Each antibody-associated autoimmune encephalitis typically presents with a recognizable blend of clinical and investigation features, which help differentiate each from alternative diagnoses. The rapid expansion of recognized antibodies and some clinical overlaps support panel-based antibody testing. The clinical-serologic picture guides the immunotherapy regime and offers valuable prognostic information. Patient care should be delivered in conjunction with autoimmune encephalitis experts.

A common genetic variant in the Neurexin family member CNTNAP2 is related to language but not communication skills in youth with Autism Spectrum Disorder.

One of the candidate genes related to language variability in individuals with Autism Spectrum Disorder (ASD) is the contactin-associated protein-like 2 gene (CNTNAP2), a member of the Neurexin family. However, due to the different assessment tools used, it is unknown whether the polymorphisms of the CNTNAP2 gene are linked to structural language skills or more general communication abilities. A total of 302 youth aged 7 to 18 years participated in the present study: 131 verbal youth with ASD (62 female), 130 typically developing (TD) youth (64 female), and 41 unaffected siblings (US) of youth with ASD (25 female). Blood samples were collected to obtain genomic DNA and processed by the Rutgers University Cell and Data Repository or using standard protocols (Gentra Puregene Blood DNA extraction kit; Qiagen). Language and verbal communication skills were screened with the Clinical Evaluation of Language Fundamental-4 (CELF-4) and Vineland-II Communication domain, subsequently. The results showed that the polymorphism of CNTNAP2 (SNP rs2710102) was related to structural language abilities, such that participants carrying the A-allele had lower language skills in comparison to the G-allele homozygotes. No relationship was found between the polymorphism of CNTNAP2 and more general communication abilities. Although the study revealed genetic mechanisms that are associated with CELF-4 measures but not Vineland-II in youth with ASD, follow-up studies are needed that will include measures of language and communication that are less correlated to each other as well as will include a group of minimally and/or non-verbal individuals with ASD.

Autism in Iraqi Children: Investigating the CNTNAP2 rs7794745 Polymorphism in the Middle Euphratesv

Objectives: This study aims to determine if the CNTNAP2 gene polymorphism at the rs7794745 locus is associated with autism spectrumdisorder (ASD) by comparing its frequency in autistic children and healthy controls. Methods: The case-control study involved a total of 150 samples, comprising 80 individuals diagnosed with autism spectrum disorder(ASD) and 70 healthy children. These participants, both male and female, had an average age of 3.5 ± 3 years for autistic individuals and4.2 ± 3 years for healthy children. Genomic analysis was performed by amplifying and scrutinizing DNA sequences through the utilizationof polymerase chain reaction (PCR) and restriction enzymes. Specifically, the genotyping of the CNTNAP2 gene at the rs7794745 locus wasaccomplished using the PCR-RFLP method. To facilitate genotyping, the isolation of DNA from peripheral blood cells sourced from healthychildren and patients. Results: Our findings indicated a statistically non-significant low-frequency distribution (P-value > 0.05) of the rs7794745 SNP in ASDpatients compared to healthy children. Conclusion: The study’s findings propose that there is no correlation between the rs7794745 polymorphism and autism spectrum disorder (ASD).

Risk of Seizure Recurrence Due to Autoimmune Encephalitis With NMDAR, LGI1, CASPR2, and GABABR Antibodies: Implications for Return to Driving.

Patients with ongoing seizures are usually not allowed to drive. The prognosis for seizure freedom is favorable in patients with autoimmune encephalitis (AIE) with antibodies against NMDA receptor (NMDAR), leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (CASPR2), and the gamma-aminobutyric-acid B receptor (GABABR). We hypothesized that after a seizure-free period of 3 months, patients with AIE have a seizure recurrence risk of <20% during the subsequent 12 months. This would render them eligible for noncommercial driving according to driving regulations in several countries. This retrospective multicenter cohort study analyzed follow-up data from patients aged 15 years or older with seizures resulting from NMDAR-, LGI1-, CASPR2-, or GABABR-AIE, who had been seizure-free for ≥3 months. We used Kaplan-Meier (KM) estimates for the seizure recurrence risk at 12 months for each antibody group and tested for the effects of potential covariates with regression models. We included 383 patients with NMDAR-, 440 with LGI1-, 114 with CASPR2-, and 44 with GABABR-AIE from 14 international centers. After being seizure-free for 3 months after an initial seizure period, we calculated the probability of remaining seizure-free for another 12 months (KM estimate) as 0.89 (95% confidence interval [CI] 0.85-0.92) for NMDAR, 0.84 (CI 0.80-0.88) for LGI1, 0.82 (CI 0.75-0.90) for CASPR2, and 0.76 (CI 0.62-0.93) for GABABR. Taking a <20% recurrence risk within 12 months as sufficient, patients with NMDAR-AIE and LGI1-AIE could be considered eligible for noncommercial driving after having been seizure-free for 3 months.

Distinct plasma metabolomic signatures differentiate autoimmune encephalitis from drug-resistant epilepsy.

Differentiating forms of autoimmune encephalitis (AE) from other causes of seizures helps expedite immunotherapies in AE patients and informs studies regarding their contrasting pathophysiology. We aimed to investigate whether and how Nuclear Magnetic Resonance (NMR)-based metabolomics could differentiate AE from drug-resistant epilepsy (DRE), and stratify AE subtypes. This study recruited 238 patients: 162 with DRE and 76 AE, including 27 with contactin-associated protein-like 2 (CASPR2), 29 with leucine-rich glioma inactivated 1 (LGI1) and 20 with N-methyl-d-aspartate receptor (NMDAR) antibodies. Plasma samples across the groups were analyzed using NMR spectroscopy and compared with multivariate statistical techniques, such as orthogonal partial least squares discriminant analysis (OPLS-DA). The OPLS-DA model successfully distinguished AE from DRE patients with a high predictive accuracy of 87.0 ± 3.1% (87.9 ± 3.4% sensitivity and 86.3 ± 3.6% specificity). Further, pairwise OPLS-DA models were able to stratify the three AE subtypes. Plasma metabolomic signatures of AE included decreased high-density lipoprotein (HDL, -(CH2)n-, -CH3), phosphatidylcholine and albumin (lysyl moiety). AE subtype-specific metabolomic signatures were also observed, with increased lactate in CASPR2, increased lactate, glucose, and decreased unsaturated fatty acids (UFA, -CH2CH=) in LGI1, and increased glycoprotein A (GlycA) in NMDAR-antibody patients. This study presents the first non-antibody-based biomarker for differentiating DRE, AE and AE subtypes. These metabolomics signatures underscore the potential relevance of lipid metabolism and glucose regulation in these neurological disorders, offering a promising adjunct to facilitate the diagnosis and therapeutics.

Neuronal autoantibodies in the cerebrospinal fluid of 148 patients with schizophrenia and 151 healthy controls

Schizophrenia is a syndrome with multiple etiologies, one of which is the potential for an autoimmune disease of the brain such as N-methyl-d-aspartate receptor (NMDAR) encephalitis, which can induce psychosis resembling schizophrenia. Here, we examined anti-neuronal autoantibodies related to psychosis using both cell- (CBA) and tissue-based assays (TBA) in the cerebrospinal fluid (CSF) of patients with chronic schizophrenia and control participants. First, we screened for the antibodies against leucine-rich glioma-inactivated 1 (LGI1), γ-aminobutyric acid B receptor (GABABR), dipeptidyl aminopeptidase-like protein 6 (DPPX), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR1/R2), and contactin-associated protein-like 2 (CASPR2) in 148 patients with schizophrenia. No antibodies were detected. Next, we performed CBA for NMDAR antibodies in 148 patients with schizophrenia and 151 age- and sex-matched controls. Although we detected relatively weak immunoreactivity for NMDAR in the CSFs of two patients with schizophrenia and three controls, no samples were positive when strict criteria were applied. For TBA in the rat hippocampus and cerebellum, we detected positive signals in the CSFs of 13 patients with schizophrenia and eight controls. Positive samples were analyzed for paraneoplastic syndrome and antinuclear antibodies using immunoblotting. The CSFs of nine patients and six controls were positive for dense fine speckle 70 (DFS70) antibodies. Additionally, antibodies against centromere protein (CENP)-A and CENP-B were detected in patients with schizophrenia. Our results suggest that autoantibodies against NMDAR, LG1, GABABR, DPPX, AMPAR1/R2, and CASPR2 are not associated with the pathogenesis of chronic schizophrenia. Moreover, we emphasize the importance of considering the effect of anti-DFS70 antibodies when analyzing autoantibodies in CSF samples. Conclusively, we obtained no evidence suggesting that the most frequent neuronal autoantibodies in the CSF play a role in the pathogenesis of schizophrenia, even in our sample.

The role of the CNTNAP2 gene in the development of autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder in which genetic and environmental factors interact in its development. Research suggests that the contactin associated protein 2 (CNTNAP2) gene may play a role in ASD pathophysiology, yet more studies involving human participants and animal models of autism are needed. One such model may be the use of prenatal valproic acid (VPA) model to induce autism-like behaviors in offspring rats. The aim of this study was twofold: (1) to examine the association of the CNTNAP2 gene rs2710102 variant with ASD in children; and (2) to examine the effect of prenatal exposure to VPA on Cntnap2 gene expression in the rat brain. The study included 167 children of European ancestry—81 diagnosed with ASD (20 girls, 61 boys; age 4.9 ± 1.4 years) and 86 controls (44 girls, 42 boys; 5.1 ± 1.2 years). In vivo experiments were conducted in 80 rats (40 with the VPA model of autism), with Cntnap2 gene expression analysis in the amygdala, hippocampus, prefrontal cortex, and cerebellum. Results demonstrated that the frequency of the CNTNAP2 gene rs2710102 GG genotype was significantly higher in children with ASD when compared with controls (33.3 vs 19.8%; OR=2.03, 95%CI [1.004, 4.102], p = 0.035), although, potentially due to bias in cohort selection, in the ASD children this polymorphism did not meet Hardy-Weinberg expectations (χ2 =5.40, p = 0.02). In addition, Cntnap2 gene expression was significantly lower (p < 0.01) in the amygdala and hippocampus of VPA rats when compared with controls, regardless of sex. These results support previous research and provide evidence for the CNTNAP2 gene as a risk factor for ASD.

Properties of the Caudal Pontine Reticular Nucleus Neurons Determine the Acoustic Startle Response in Cntnap2 KO Rats.

Rats with a loss-of-function mutation in the contactin-associated protein-like 2 (Cntnap2) gene have been validated as an animal model of autism spectrum disorder (ASD). Similar to many autistic individuals, Cntnap2 knock-out rats (Cntnap2-⁣/-) are hyperreactive to sound as measured through the acoustic startle response. The brainstem region that mediates the acoustic startle response is the caudal pontine reticular nucleus (PnC), specifically giant neurons in the PnC. We previously reported a sex-dependent genotypic effect in the sound-evoked neuronal activity recorded from the PnC, whereby female Cntnap2-⁣/- rats had a dramatic increase in sound-evoked responses compared with wildtype counterparts, but male Cntnap2-⁣/- rats showed only a modest increase in PnC activity that cannot fully explain the largely increased startle in male Cntnap2-⁣/- rats. The present study therefore investigates activation and histological properties of PnC giant neurons in Cntnap2-⁣/- rats and wildtype littermates. The acoustic startle response was elicited by presenting rats with 95 dB startle pulses before rats were euthanized. PnC brain sections were stained and analyzed for the total number of PnC giant neurons and the percentage of giant neurons that expressed phosphorylated cAMP response element binding protein (pCREB) in response to startle stimuli. Additionally, in vitro electrophysiology was conducted to assess the resting state activity and intrinsic properties of PnC giant neurons. Wildtype and Cntnap2-⁣/- rats had similar total numbers of PnC giant neurons and similar levels of baseline pCREB expression, as well as similar numbers of giant neurons that were firing at rest. Increased startle magnitudes in Cntnap2-⁣/- rats were associated with increased percentages of pCREB-expressing PnC giant neurons in response to startle stimuli. Male rats had increased pCREB-expressing PnC giant neurons compared with female rats, and the recruited giant neurons in males were also larger in soma size. Recruitment and size of PnC giant neurons are important factors for regulating the magnitude of the acoustic startle response in Cntnap2-⁣/- rats, particularly in males. These findings allow for a better understanding of increased reactivity to sound in Cntnap2-⁣/- rats and in CNTNAP2-associated disorders such as ASD.

Neuronal antibodies in nonparaneoplastic autoimmune cerebellar ataxias.

To describe relevant advances in nonparaneoplastic autoimmune cerebellar ataxias (ACA) with neuronal antibodies. Apart from metabotropic glutamate receptor 1(mGluR1) antibodies, in recent years, the number of neuronal antibodies against surface antigens in ACA has increased with the description of glutamate kainate receptor subunit 2 (GluK2) antibodies in young patients with cerebellitis. Around 20% of patients with contactin-associated protein-like 2 (CASPR2) encephalitis also present prominent cerebellar ataxia. However, isolate cerebellar ataxia is unusual (<4%). Outcome in patients with neuronal antibodies against surface antigens remains suboptimal despite the cerebellar ataxia probably is antibody-mediated.Concerning neuronal antibodies against intracellular antigens, up to 25% of patients with glutamic acid decarboxylase (GAD) antibodies present transient episodes of vertigo or diplopia that antedate the development of the ACA. There is in-vitro evidence that septin-5 is partially exposed to the membrane and the antibodies may interfere with septin-5 function. The clinical significance of the remaining antibodies against intracellular antigens remains unclear. The number of antibodies against surface antigens is increasing in ACA, but the response to the immunotherapy remains suboptimal. More studies are needed to clarify the role of most of the antibodies against intracellular antigens described in these patients.

Contactin-associated protein-like 2 (CNTNAP2) mutations impair the essential α-secretase cleavages, leading to autism-like phenotypes

Mutations in the Contactin-associated protein-like 2 (CNTNAP2) gene are associated with autism spectrum disorder (ASD), and ectodomain shedding of the CNTNAP2 protein plays a role in its function. However, key enzymes involved in the C-terminal cleavage of CNTNAP2 remain largely unknown, and the effect of ASD-associated mutations on this process and its role in ASD pathogenesis remain elusive. In this report we showed that CNTNAP2 undergoes sequential cleavages by furin, ADAM10/17-dependent α-secretase and presenilin-dependent γ-secretase. We identified that the cleavage sites of ADAM10 and ADAM17 in CNTNAP2 locate at its C-terminal residue I79 and L96, and the main α-cleavage product C79 by ADAM10 is required for the subsequent γ-secretase cleavage to generate CNTNAP2 intracellular domain (CICD). ASD-associated CNTNAP2 mutations impair the α-cleavage to generate C79, and the inhibition leads to ASD-like repetitive and social behavior abnormalities in the Cntnap2-I1254T knock-in mice. Finally, exogenous expression of C79 improves autism-like phenotypes in the Cntnap2-I1254T knock-in and Cntnap2−/− knockout mice. This data demonstrates that the α-secretase is essential for CNTNAP2 processing and its function. Our study indicates that inhibition of the cleavage by pathogenic mutations underlies ASD pathogenesis, and upregulation of its C-terminal fragments could have therapeutical potentials for ASD treatment.

Genetic Insights: Examining CNTNAP2 rs7794745 Gene Polymorphism and Its Impact on ABLLS Assessment in Middle Euphrates Children in Iraq with Autism Spectrum Disorder

Objective: examine the effect of CNTNAP2 gene polymorphism on behavioral therapy response in Iraqi children with autism spectrum disorder using ABLLS-r.&#x0D; Methods: In this study, 150 samples for autism spectrum disorder were obtained from AL-SIBTEIN ACADEMY, however owing to many challenges, the final number of samples was 50 patients. Polymerase Chain Reaction-Restriction refers to a technique that combines the use of polymerase chain reaction (PCR) with restriction enzymes to amplify and analyze certain DNA sequences. Fragment Length Polymorphism (PCR-RFLP) was used to genotype the CNTNAP2 gene at rs7794745. All 25 ABLLS-R repertoires and all four primary components had their dependent parameters determined by aggregating and converting the ABLLS data to a percentage. This provided us with the proportion of finished assignments from each repertoire.&#x0D; Results: After correlating the genotype data (AA/AT/TT) with the behavioral therapy response as indicated by ABLLS-R, we only discovered a statistically significant difference between the frequency of AA/TT genotypes in the rs7794745 variant in patients and the social interaction domain. Conversely, the remaining 24 subdomains exhibited no discernible correlation.&#x0D; Conclusion: This research topic could provide significant information on targeting and categorizing which skill areas need to be developed based on genetic models' influence.

Ultrahigh frequencies of peripherally matured LGI1- and CASPR2-reactive B cells characterize the cerebrospinal fluid in autoimmune encephalitis

Intrathecal synthesis of central nervous system (CNS)-reactive autoantibodies is observed across patients with autoimmune encephalitis (AE), who show multiple residual neurobehavioral deficits and relapses despite immunotherapies. We leveraged two common forms of AE, mediated by leucine-rich glioma inactivated-1 (LGI1) and contactin-associated protein-like 2 (CASPR2) antibodies, as human models to comprehensively reconstruct and profile cerebrospinal fluid (CSF) B cell receptor (BCR) characteristics. We hypothesized that the resultant observations would both inform the observed therapeutic gap and determine the contribution of intrathecal maturation to pathogenic B cell lineages. From the CSF of three patients, 381 cognate-paired IgG BCRs were isolated by cell sorting and scRNA-seq, and 166 expressed as monoclonal antibodies (mAbs). Sixty-two percent of mAbs from singleton BCRs reacted with either LGI1 or CASPR2 and, strikingly, this rose to 100% of cells in clonal groups with ≥4 members. These autoantigen-reactivities were more concentrated within antibody-secreting cells (ASCs) versus B cells (P < 0.0001), and both these cell types were more differentiated than LGI1- and CASPR2-unreactive counterparts. Despite greater differentiation, autoantigen-reactive cells had acquired few mutations intrathecally and showed minimal variation in autoantigen affinities within clonal expansions. Also, limited CSF T cell receptor clonality was observed. In contrast, a comparison of germline-encoded BCRs versus the founder intrathecal clone revealed marked gains in both affinity and mutational distances (P = 0.004 and P < 0.0001, respectively). Taken together, in patients with LGI1 and CASPR2 antibody encephalitis, our results identify CSF as a compartment with a remarkably high frequency of clonally expanded autoantigen-reactive ASCs whose BCR maturity appears dominantly acquired outside the CNS.