Hook-effect in MAGLUMI immunoassay for serum anti-GAD antibodies in neurological disorders: When "wrong" matrix is the right choice.

Antibodies against glutamic acid decarboxylase (anti-GAD) are a valuable diagnostic tool to detect severe autoimmune conditions as type 1 diabetes mellitus (T1DM) and anti-GAD related neurological disorders, having the latter more often anti-GAD concentrations in serum multiple times higher than in the former. Automated immunoassays, either with ELISA or chemiluminescent technology, are validated for diagnostic use in serum with analytical ranges suitable for T1DM diagnosis. In a patient presenting with a suspected autoimmune ataxia, anti-GAD testing on an automated chemiluminescent immunoassay (CLIA) resulted in slightly abnormal concentrations in serum (39.2 KIU/L) and very high concentrations in CSF (>280 KIU/L), thus prompting to proceed to serum dilutions to exclude a false negative result and a misdiagnosis. Different dilutions of serum resulted in nonlinear concentrations with endpoint result of 276,500 KIU/L at dilution 1:1000. CSF dilution was instead linear with endpoint result of 4050 KIU/L. In this case report we found that anti-GAD testing in CSF was essential to establish the clinical diagnosis and to suspect hook-effect in serum due to the excess of autoantibodies in this severe autoimmune condition.

Therapeutic role of plasma exchange in the management of stiff person syndrome: experience from a tertiary care centre.

INTRODUCTION: The stiff person syndrome (SPS) is a rare and disabling neurological disorder characterized by muscle stiffness, painful spasms and rigidity involving the proximal and axial limb muscles, with an estimated incidence of 1 case per million per year. The first line of treatment for symptomatic management includes gamma-aminobutyric acid (GABA)ergic agonists, benzodiazepines and baclofen. The therapeutic plasma exchange (TPE), alone or as an adjuvant to other forms of immunomodulation, has been used as a therapeutic option, particularly in refractory cases. METHODS: An observational study was performed to review SPS patient symptoms, comorbidities, electromyography (EMG) studies and treatment, identifying autoantibodies, therapeutic plasma exchange (TPE) procedural details and clinical response. MAIN RESULTS: Five patients (4 male and one female) were treated with TPE during the study period as adjuvant therapy. The average age was 47 years (range 34 - 61 years), and anti-glutamic acid decarboxylase 65-kilodalton isoform (anti-GAD65) antibodies were positive in 80 % (4/5) of the patient population. All patients received immunosuppressive drugs along with TPE. Four patients received TPE during the first admission and one received it during the third hospital admission. All patients showed good improvement immediately after TPE, but it was not a sustainable effect. CONCLUSION: TPE may be helpful as adjuvant therapy for SPS patients to provide relief from clinical symptoms.

Reaching the Diagnosis of Checkpoint Inhibitor-Induced Diabetes Mellitus in Different Clinical Scenarios: A Real-World Application of Updated Diagnostic Criteria.

BACKGROUND: Checkpoint inhibitor (CPI)-associated diabetes mellitus (CPI-DM) is a rare immune-related adverse event (irAE) that presents with variable clinical manifestations. Data about its pathogenesis have not yet been adequately studied. METHODS: Applying the recently updated diagnostic criteria from the American Diabetes Association, we retrospectively reviewed the medical records of all CPI-treated patients referred to our endocrinological unit for managing their endocrine irAEs and analyzed the incidence of CPI-DM, its clinical characteristics, and its management. RESULTS: Among the 326 CPI-treated patients with endocrine irAEs, 4 patients met the updated criteria for the diagnosis of CPI-DM, representing 1.22% of all endocrine irAEs in our cohort. These four patients presented with distinct clinical scenarios regarding the irAE onset, the underlying malignancy, the administered CPI regimen, and the type of circulating autoantibodies. CONCLUSION: The variable presentation of CPI-DM and the non-standard sensitivity of the presence of the type 1 DM traditional autoantibodies highlight the need for distinct guidelines and increased awareness of its diagnosis and management.

Efgartigimod beyond myasthenia gravis: the role of FcRn-targeting therapies in stiff-person syndrome.

Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder characterized by high titers of antibodies against glutamic acid decarboxylase (GAD) causing impaired GABAergic inhibitory neurotransmission. To date, there is not a defined therapy for such condition, but immunomodulating therapies, such as plasma exchange, intravenous immunoglobulins, and rituximab, have been widely used in clinical practice. However, the efficacy and tolerability of these treatments is not well established. Efgartigimod, a new neonatal Fc receptor (FcRn) blocker, is a human IgG1 antibody Fc fragment engineered with increased affinity for FcRn binding, leading to a reduction in IgGs levels, including pathogenic IgG autoantibody showing promising results in neurological autoimmune disorders and has been approved for the treatment of AChR-seropositive generalized myasthenia gravis (MG). In this study, we report and describe the first data on treatment with efgartigimod in three patients affected by both AChR-seropositive generalized MG and anti-GAD-seropositive SPS. Patients were followed since the start of efgartigimod and for the whole treatment period (12 weeks). MG symptoms were assessed with the "MG activity of daily living score" and the Quantitative Myasthenia Gravis score, while SPS ones were assessed with the "SPS activity of daily living score"; muscle strength was assessed with the Medical Research Council Sum score; the overall disability from MG and SPS was assessed by the modified Rankin Scale. All patients showed an improvement in symptoms of both SPS and MG after 2 cycles of treatment. Our data suggest that efgartigimod may be considered as a candidate drug for SPS and other autoantibody-mediated neurological disorders.

Expanding clinical profiles and prognostic markers in stiff person syndrome spectrum disorders.

OBJECTIVE: To describe the clinical features of a cohort of individuals with stiff person syndrome spectrum disorders (SPSD) and identify potential early predictors of future disability. BACKGROUND: There is a need to better understand the full spectrum of clinical and paraclinical features and long-term impact of SPSD. DESIGN/METHODS: Observational study from 1997 to 2022 at Johns Hopkins. Clinical phenotypes included classic SPS, partial SPS (limb or trunk limited), SPS-plus (classic features plus cerebellar/brainstem involvement), and progressive encephalomyelitis with rigidity and myoclonus (PERM). Outcome measures were modified Rankin scale (mRS) and use of assistive device for ambulation. Multivariate logistic regression was used to assess significant predictors of outcomes. RESULTS: Cohort included 227 individuals with SPSD with mean follow-up of 10 years; 154 classic, 48 SPS-plus, 16 PERM, and 9 partial. Mean age at symptom onset was 42.9 ± 14.1 years, majority were white (69.2%) and female (75.8%). Median time to diagnosis was 36.2 months (longest for SPS-plus and PERM) and 61.2% were initially misdiagnosed. Most had systemic co-morbidities and required assistive devices for ambulation. Female sex (OR 2.08; CI 1.06-4.11) and initial brainstem/cerebellar involvement (OR 4.41; CI 1.63-14.33) predicted worse outcome by mRS. Older age at symptom onset (OR 1.04; CI 1.01-1.06), female sex (OR 1.99; CI 1.01-4.01), Black race (OR 4.14; CI 1.79-10.63), and initial brainstem/cerebellar involvement (OR 2.44; CI 1.04-7.19) predicted worse outcome by use of assistive device. Early implementation of immunotherapy was associated with better outcomes by either mRS (OR 0.45; CI 0.22-0.92) or use of assistive device (OR 0.79; CI 0.66-0.94). CONCLUSIONS: We present the expanding phenotypic variability of this rare spectrum of disorders and highlight potential predictors of future disability.

A case report of anti-GAD65 antibody-positive autoimmune encephalitis in children associated with autoimmune polyendocrine syndrome type-II and literature review.

Background: Glutamic acid decarboxylase (GAD) is the rate-limiting enzyme for the synthesis of gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Antibodies against glutamic acid decarboxylase (GAD) are associated with various neurologic conditions described in patients, including stiff person syndrome, cerebellar ataxia, refractory epilepsy, and limbic and extra limbic encephalitis. While there are few case reports and research on anti-GAD65 antibody-associated encephalitis in adults, such cases are extremely rare in pediatric cases. Methods: For the first time, we report a case of anti-GAD65-positive autoimmune encephalitis associated with autoimmune polyendocrine syndrome (APS) type II. We reviewed previously published pediatric cases of anti-GAD65 autoimmune encephalitis to discuss their clinical features, laboratory tests, imaging findings, EEG patterns, and prognosis. Case presentation: An 8-year-old, male child presented to the outpatient department after experiencing generalized convulsions for twenty days. The child was admitted for epilepsy and had received oral sodium valproate (500 mg/day) in another center, where investigations such as USG abdomen and MRI brain revealed no abnormalities, however, had abnormal EEG with diffuse mixed activity in the left anterior middle prefrontal temporal region. On the follow-up day, a repeat blood test showed a very low serum drug concentration of sodium valproate hence the dose was increased to 750 mg/day. Then, the child experienced adverse effects including increased sleep, thirst, and poor appetite, prompting the parents to discontinue the medication. A repeat MRI showed increased signals on FLAIR sequences in the right hippocampus hence admitted for further management. The child's past history included a diagnosis of hypothyroidism at the age of 4, and receiving levothyroxine 75 mcg once daily. His parents are healthy with no history of any similar neurological, autoimmune, or genetic diseases, but his uncle had a history of epilepsy. At presentation, he had uncontrolled blood glucose levels with elevated HbA1c levels. Additionally, the serum and CSF autoantibodies were positive against the anti-GAD65 antibody with the titer of 1:100 and 1:32 respectively. The patient was managed with a mixed type of insulin regimen and received first-line immunotherapy (intravenous immunoglobulin, IVIG) for five consecutive days, followed by oral prednisone and sodium valproate as an antiepileptic drug. Upon achieving a favorable clinical outcome, the patient was discharged with oral medications. Results: Among the 15 pediatric patients reported in this literature, nine presented with limbic encephalitis (LE), three with extralimbic encephalitis (ELE), and three with a combination of limbic and extralimbic encephalitis. Most of these cases exhibited T2-W FLAIR hyperintensities primarily localized to the temporal lobes in the early phase, progressing to hippocampal sclerosis/atrophy in the later phase on MRI. EEG commonly showed slow or spike waves on frontotemporal lobes with epileptic discharges. Prognostic factors varied among patients, with some experiencing persistent refractory seizures, type-1 diabetes mellitus (T1DM), persistent memory impairment, persistent disability requiring full assistance, and, in severe cases, death. Conclusion: Our findings suggest that anti-GAD65 antibody-positive autoimmune encephalitis patients may concurrently present with other APS. Our unique case presented with multiple endocrine syndromes and represents the first reported occurrence in children. Early diagnosis and timely initiation of immunotherapy are crucial for improving clinical symptoms and reducing the likelihood of relapses or permanent disabilities. Therefore, emphasis should be placed on prompt diagnosis and appropriate treatment implementation to achieve better patient outcomes.

Susac Syndrome and Role of Therapeutic Plasma Exchange: A Case Report.

Susac syndrome is a relatively uncommon autoimmune disease that predominantly affects young females, with the highest incidence between the third and fourth decade of life, presenting classically with encephalopathy, various CNS dysfunctions, visual impairment due to retinal artery occlusion, and hearing loss. Despite treatment options, such as glucocorticoid steroids, intravenous immunoglobulin, methotrexate, azathioprine, mycophenolate mofetil, or rituximab, some patients with Susac syndrome remain refractory to therapy. We present a case report of a 38-year-old female with refractory Susac syndrome who was treated successfully with plasmapheresis.

Concomitant Crohn's Disease and Anti-Glutamic Acid Decarboxylase (GAD)-Associated Autoimmune Encephalitis: A Case Report.

Crohn's disease is an inflammatory, autoimmune disorder that predominantly affects the intestines but can also affect extraintestinal organs. Certain neurological conditions, such as autoimmune encephalitis, can develop along with this disease. In this case report, we present a case of anti-glutamic acid decarboxylase (GAD) antibody-associated autoimmune encephalitis that occurred shortly after the diagnosis of Crohn's disease and was unrelated to the treatment and nutritional deficiencies. After a significant weight loss (24 kg) and persistent diarrhea, the patient was diagnosed with Crohn's disease by colonoscopy and biopsy. Within two weeks after the diagnosis, he experienced altered consciousness and memory impairment, followed by a rapid deterioration in consciousness and respiratory distress, leading to intubation and admission to the intensive care unit. His brain MRI revealed asymmetrical diffuse cortical diffusion restrictions, hyperintense signals on fluid-attenuated inversion recovery (FLAIR) sequences, and diffuse pachymeningeal contrast enhancement involving both cingulate gyri, bilateral insular cortices, amygdalae, hippocampi, and the right precuneus. Analysis of cerebrospinal fluid (CSF) revealed a slight elevation of CSF proteins, and the patient tested positive for serum anti-GAD antibodies. The patient responded favorably to a seven-day course of intravenous methylprednisolone, five days of intravenous immunoglobulin (IVIG), and oral corticosteroids. Subsequent treatment consisted of monthly IVIG, azathioprine, and vedolizumab, resulting in no neurologic sequelae except mild amnesia. A follow-up MRI at three months showed a nearly complete disappearance of the lesions. This is the first reported case of anti-GAD-associated encephalitis occurring in the presence of Crohn's disease.

Anti-GAD Encephalitis Following COVID-19 Vaccination: A Case Report.

Since December 2020, a significantly higher number of people worldwide have been vaccinated for coronavirus disease 2019 (COVID-19). Neurological complications have been reported after these vaccines, although a definitive causal relationship has not been proven in the available literature. We describe a 51-year-old man presenting with anti-glutamic acid decarboxylase (anti-GAD) antibody positive autoimmune encephalitis with progressive cognitive impairment and behavioral abnormalities, presenting shortly after the second dose of mRNA COVID-19 vaccine, possibly representing a serious vaccine-related adverse event. Response to high-dose steroid and intravenous immunoglobulin treatment was positive. As many people around the world have been vaccinated against COVID-19, this case shows that autoimmune encephalitis and even anti-GAD antibody positive autoimmune encephalitis can develop as a side effect after this new vaccine, but with early diagnosis and appropriate treatment, the clinic can have a good prognosis. Observational studies with large numbers of patients are needed to explain causality.

Paraneoplastic Cerebellar Degeneration Accompanied by Seropositivity for Anti-GAD65, Anti-SOX-1 and Anti-VGCC Antibodies Due to Small-cell Lung Cancer.

Paraneoplastic cerebellar degeneration (PCD) is a paraneoplastic neurological syndrome that is rarely accompanied by seropositivity with a combination of multiple antibodies. We herein report a 50-year-old man with PCD accompanied by small-cell lung cancer (SCLC). This patient was seropositive for anti-glutamic acid decarboxylase 65, anti-SRY-related HMG-box gene 1 and anti-voltage-gated calcium channel antibodies. After chemoradiation therapy without immunotherapy, cerebellar ataxia of the trunk and limbs markedly improved, along with a notable amelioration of SCLC. This case suggests that tumor therapy should be started immediately and that a panel of anti-neuronal antibodies should be evaluated when PCD with SCLC is suspected.

Prevalence of Positivity for Diabetes-Associated Autoantibodies in Individuals with Type 2 Diabetes and Their Further Characterisation: Cross-sectional Study from Slovakia.

BACKGROUND: Individuals initially diagnosed with type 2 diabetes (T2D) might exhibit positivity for diabetes-associated autoantibodies (DAA +). We investigated the prevalence of DAA positivity in a group of individuals with T2D who were referred to a tertiary diabetes centre within a pre-specified period of time. We aimed to identify characteristics linked with DAA positivity by comparing DAA + individuals with their DAA-negative counterparts. METHODS: This was a cross-sectional study into which all T2D patients referred to the National Institute of Endocrinology and Diabetology, Lubochna, Slovakia, between 1 January and 30 June 2016 were included. Data on > 70 participants' characteristics, including antibodies against glutamic acid decarboxylase (anti-GAD65), insulinoma-associated antigen IA-2 (IA-2A) and insulin (IAA), were collected. RESULTS: Six hundred and ninety-two individuals (387, 55.6% female) with a median (range) age of 62 (24-83) years, HbA1c of 8.9 (5.0-15.7)% [74 (31-148 mmol/mol)] and diabetes duration of 13.0 (0-42) years were analysed. One hundred and forty-five (145/692, 21.0%) tested positive for at least one DAA; 136/692 (19.7%) were positive for anti-GAD65, 21/692 (3.0%) were positive for IA-2A and 9/692 (1.3%) were positive for IAA. Only 84.9% of the DAA + individuals aged > 30 years at the time of diabetes diagnosis met the current diagnostic criteria for latent autoimmune diabetes of adults (LADA). DAA + differed from DAA - individuals in multiple characteristics, including the incidence of hypoglycaemia. CONCLUSION: Several pathological processes linked with distinct types of diabetes can develop in parallel, including insulin resistance and autoimmune insulitis. In this single-centre cross-sectional study from Slovakia, we report a higher than previously published prevalence of DAA positivity in a group of individuals with a formal diagnosis of T2D.

Co-occurrence of Anti-GAD65 Syndrome, Type 1 Diabetes Mellitus, and Focal Seizures With Impaired Awareness.

Glutamic acid decarboxylase (GAD) is an intracellular enzyme found in the presynaptic end of nerve terminals that functions to synthesize ​​gamma-aminobutyric acid (GABA) via decarboxylation. Autoantibodies to the GAD65 isoform have been found in high levels in neurological disorders including stiff person syndrome (SPS), autoimmune encephalitis, and refractory epilepsy. Low levels of anti-GAD65 have also been noted in type 1 diabetes mellitus. We present the unusual case of a woman with a longstanding history of focal seizures with impaired awareness and type 1 diabetes mellitus who was found to have extremely high titers of anti-GAD65 and clinical presentation suggestive of stiff person syndrome. This case highlights the increasing significance of autoimmune etiologies within neurologic disorders, as well as the importance of maintaining a high index of suspicion for rare anti-GAD65 syndromes. Although uncommon and with an unclear pathophysiology, we discuss the importance of establishing SPS diagnostic criteria to facilitate timely diagnosis and quickly direct patient management towards immunotherapy.

Secondary immunoreaction in patients with neurosyphilis and its relevance to clinical outcomes.

Background and purpose: Several reported cases of autoimmune conditions such as anti-NMDAR encephalitis and neuromyelitis optica (AQP4) have been considered to be potentially secondary to Treponema pallidum infection. Since the role of immune impairment in neurosyphilis is unclear, in this retrospective study, we examined the correlation of the immune impairment in patients with neurosyphilis with their clinical characteristics and outcomes. Methods: Clinical information was collected from patients with neurosyphilis in our center from January 2019 to December 2021. Cerebrospinal fluid (CSF) samples were subjected to indirect immunofluorescence tissue-based assay (IIF-TBA) on mouse brain sections and cell-based assay (CBA). The clinical characteristics and treatment outcomes of TBA-positive and-negative patients were compared. Results: A total number of 81 patients diagnosed with neurosyphilis were included. The results of the CBA tests showed that three cases had anti-NMDAR, AQP4, or GAD65 antibodies, respectively. By TBA test, 38 patients (38/81, 46.9%) had positive immunostains, including staining of neuronal cells in 21 cases (21/38, 55.3%), glial cells in 11 cases (11/38, 28.9%), and neuronal and glial cells in six cases (6/38, 15.8%). We then compared the clinical characteristics and treatment outcomes between the TBA-positive and-negative patients and found that TBA-positive staining was significantly correlated with syphilis antibody titers (p = 0.027 for serum and p = 0.006 for CSF) and head MRI abnormalities (p < 0.001 for parenchymal abnormalities and p = 0.013 for white matter lesions). The cognitive prognosis of TBA-positive neurosyphilis patients was significantly worse than that of TBA-negative patients (p < 0.001). Conclusion: The correlation between the TBA results and clinical data of our neurosyphilis patients imply the presence of secondary immune damage, which affected their prognosis. Therefore, TBA can be used as an additional biomarker for neurosyphilis patient prognosis.

Anti-Glutamic Acid Decarboxylase (GAD) 65 Encephalitis Mistaken for Herpes Encephalitis and Hashimoto's Encephalitis (HE): A Case Report.

Autoimmune encephalitis is increasingly recognized in clinical practice. We are presenting a 72-year-old female patient who initially presented with a new onset seizure with temporal lobe abnormality on imaging. This was initially attributed to herpes encephalitis although herpes polymerase chain reaction (PCR) was negative. The patient was treated with acyclovir and antiepileptic medication (AEM) with some clinical improvement. She presented again with refractory seizure evolving to status epilepticus. Escalation of AEMs was pursued and positive anti-thyroid peroxidase (TPO) antibody prompted consideration of Hashimoto's encephalitis (HE) and treatment with high-dose corticosteroids and intravenous immunoglobulin (IVIG). However, poor response to steroid argued against HE, and extended autoimmune encephalitis panel revealed positive anti-glutamic acid decarboxylase (GAD) antibody. This case raises the clinical pearl that anti-thyroid antibodies, e.g anti-TPO antibody, can be seen in those with autoimmune encephalopathies other than HE and HE remains a diagnosis of exclusion. It also helps to remind clinicians that a new onset refractory seizure even with temporal lobe changes is not pathognomonic for herpes encephalitis, and although negative serology does not rule out the diagnosis, it is recommended to rule out autoimmune encephalitis as it shares similar clinical and radiological picture.

Musicogenic seizures in temporal lobe epilepsy: Case reports based on ictal source localization analysis.

Musicogenic epilepsy is a rare form of reflex epilepsy in which seizures are provoked by music. Different musicogenic stimuli have been identified: pleasant/unpleasant music or specific musical patterns. Several etiologies have been uncovered, such as focal cortical dysplasia, autoimmune encephalitis, tumors, or unspecific gliosis. In this article, we report two patients with musicogenic seizures. The first patient was diagnosed with structural temporal lobe epilepsy. Her seizures were elicited by music that she liked. Interictal and ictal video-electroencephalography (video-EEG) and signal analysis using independent component analysis revealed the right temporal lobe seizure onset extending over the neocortical regions. The patient underwent right temporal lobectomy (including the amygdala, the head, and the body of the hippocampus) and faced an Engel IA outcome 3 years post-surgery. The second patient was diagnosed with autoimmune temporal lobe epilepsy (GAD-65 antibodies). Her seizures were triggered by contemporary hit radio songs without any personal emotional significance. Interictal and ictal video-electroencephalography (video-EEG) and independent component analysis highlighted the left temporal lobe seizure onset extending over the neocortical regions. Intravenous immunoglobulin therapy was initiated, and the patient became seizure-free at 1 year. In conclusion, musicogenic seizures may be elicited by various auditory stimuli, the presence or absence of an emotional component offering an additional clue for the underlying network pathophysiology. Furthermore, in such cases, the use of independent component analysis of the scalp EEG signals proves useful in revealing the location of the seizure generator, and our findings point toward the temporal lobe, both mesial and neocortical regions.

Paraneoplastic stiff-person syndrome with lung cancer: a case report and literature review.

Stiff person syndrome is a rare autoimmune disease of the central nervous system that manifests as stiffness and painful spasms of the trunk axis and lower limb muscles. Benzodiazepines are the first choice for the clinical treatment of the disease. We reported a case of SPS. The patient presented with stiffness and convulsions of lower limbs, weakness after convulsions, falling off easily, abdominal muscle stiffness, and painful spasms lasting for several minutes and alleviating spontaneously. This was caused or aggravated by fatigue or mental stimulation. Left stiffness and weakness of the muscle after relief was present. A chest-enhanced computed tomography scan (CT) suggested two large ground glass nodules in the upper lobe of the left lung. Biopsy pathology indicated the nodules as adenocarcinoma in situ. The patient's symptoms were significantly relieved after treatment with clonazepam and diazepam combined with pregabalin. The clinical manifestations of SPS vary among patients. The symptoms of the disease are mild or severe. Early identification and treatment can improve the prognoses of these patients.

Advances in the Pathogenesis of Auto-antibody-Induced Cerebellar Synaptopathies.

The presence of auto-antibodies that target synaptic machinery proteins was documented recently in immune-mediated cerebellar ataxias. The autoantigens include glutamic acid decarboxylase 65 (GAD65), voltage-gated Ca2+ channel (VGCC), metabotropic glutamate receptor type 1 (mGluR1), and glutamate receptor delta (GluRdelta). GAD65 is involved in the synthesis, packaging, and release of GABA, whereas the other three play important roles in the induction of long-term depression (LTD). Thus, the auto-antibodies toward these synaptic molecules likely impair fundamental synaptic machineries involved in unique functions of the cerebellum, potentially leading to the development of cerebellar ataxias (CAs). This concept has been substantiated recently by a series of physiological studies. Anti-GAD65 antibody (Ab) acts on the terminals of inhibitory neurons that suppress GABA release, whereas anti-VGCC, anti-mGluR1, and anti-GluR Abs impair LTD induction. Notably, the mechanisms that link synaptic dysfunction with the manifestations of CAs can be explained by disruption of the "internal models." The latter can be divided into three levels. First, since chained inhibitory neurons shape the output signals through the mechanism of disinhibition/inhibition, impairments of GABA release and LTD distort the conversion process from the "internal model" to the output signals. Second, these antibodies impair the induction of synaptic plasticity, rebound potentiation, and LTD, on Purkinje cells, resulting in loss of restoration and compensation of the distorted "internal models." Finally, the cross-talk between glutamate and microglia/astrocytes could involve a positive feedback loop that accelerates excitotoxicity. This mini-review summarizes the pathophysiological mechanisms and aims to establish the basis of "auto-antibody-induced cerebellar synaptopathies."

Celiac And Autoimmune Thyroid Disease In Patients With Anti-Gad Positive Type-1 Diabetes Mellitus.

BACKGROUND: Type-1 diabetes mellitus (T1DM) and autoimmune thyroid disease can occur concomitantly and patients with TIDM have a high risk of other autoimmune conditions like thyroid disease and celiac disease. This study aimed to analyze the association of anti-GAD positive T1DM with anti-thyroid antibodies and celiac disease. METHODS: This cross-sectional study was conducted at the Department of Paediatric Endocrinology & Diabetes, National Institute of Child Health, Karachi Pakistan from July 2022 to December 2022. A total of 115 children of both genders aged between 1-18 years having known T1DM were analyzed. Children with chronic kidney disease or chronic liver disease were excluded. Those children were also not included whose parents/caregivers did not wish their children to be part of this research. The blood sample of each child was taken in a sterilized container and sent to an institutional laboratory for biochemical investigations. RESULTS: In a total of 115 patients, 67 (58.3%) were female and 48 (41.7%) males. The mean age was 8.87±3.43 (ranging between 1.5-17 years). The mean HbA1c was 11.86±7.31%. It was found that anti-GAD IgG was having signification association with celiac disease (p<0.001). Significant correlation of anti-GAD positive antibodies with Ttg-IgG antibodies (correlation coefficient=0.303, p=0.001), thyroid peroxidase antibodies (correlation coefficient=0.228, p=0.001). CONCLUSIONS: High proportions of children with anti-GAD positive T1DM patients were found to have thyroid disorders and celiac disease. A significant correlation was found between anti-GAD positive antibodies, celiac disease and anti-thyroglobulin antibodies.

Autoimmune meningoencephalitis associated with anti-glutamic acid decarboxylase antibody following COVID-19 infection: A case report.

Anti-glutamic acid decarboxylase (Anti-GAD) are associated with various neurologic condition; but no meningitis has been reported with it, so far. Evidence demonstrates the associated of autoimmune meningoencephalitis with COVID-19 infection. Here, we report a 44-year-old female with progressive loss of consciousness with anti-GAD65 meningoencephalitis 1 month after COVID-19 infection.