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Background: Defects in GNAO1, the gene encoding the major neuronal G‐protein Gαo, are related to neurodevelopmental disorders, epilepsy, and movement disorders. Nevertheless, there is a poor understanding of how molecular mechanisms explain the different phenotypes. Objectives: We aimed to analyze the clinical phenotype and the molecular characterization of GNAO1‐related disorders. Methods: Patients were recruited in collaboration with the Spanish GNAO1 Association. For patient phenotyping, direct clinical evaluation, analysis of homemade‐videos, and an online questionnaire completed by families were analyzed. We studied Gαo cellular expression, the interactions of the partner proteins, and binding to guanosine triphosphate (GTP) and G‐protein‐coupled receptors (GPCRs). Results: Eighteen patients with GNAO1 genetic defects had a complex neurodevelopmental disorder, epilepsy, central hypotonia, and movement disorders. Eleven patients showed neurological deterioration, recurrent hyperkinetic crisis with partial recovery, and secondary complications leading to death in three cases. Deep brain stimulation improved hyperkinetic crisis, but had inconsistent benefits in dystonia. The molecular defects caused by pathogenic Gαo were aberrant GTP binding and hydrolysis activities, an inability to interact with cellular binding partners, and reduced coupling to GPCRs. Decreased localization of Gαo in the plasma membrane was correlated with the phenotype of "developmental and epileptic encephalopathy 17." We observed a genotype–phenotype correlation, pathogenic variants in position 203 were related to developmental and epileptic encephalopathy, whereas those in position 209 were related to neurodevelopmental disorder with involuntary movements. Milder phenotypes were associated with other molecular defects such as del.16q12.2q21 and I344del. Conclusion: We highlight the complexity of the motor phenotype, which is characterized by fluctuations throughout the day, and hyperkinetic crisis with a distinct post‐hyperkinetic crisis state. We confirm a molecular‐based genotype–phenotype correlation for specific variants. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Previous studies have suggested a relationship between the number of CAG triplet repeats in the HTT gene and neurodegenerative diseases not related to Huntington's disease (HD). This study seeks to investigate whether the number of CAG repeats of HTT is associated with the risk of developing certain tauopathies and its influence as a modulator of the clinical and neuropathological phenotype. Additionally, it aims to evaluate the potential of polyglutamine staining as a neuropathological screening. We genotyped the HTT gene CAG repeat number and APOE‐ℰ isoforms in a cohort of patients with neuropathological diagnoses of tauopathies (n=588), including 34 corticobasal degeneration (CBD), 98 progressive supranuclear palsy (PSP) and 456 Alzheimer's disease (AD). Furthermore, we genotyped a control group of 1070 patients, of whom 44 were neuropathologic controls. We identified significant differences in the number of patients with pathological HTT expansions in the CBD group (2.7%) and PSP group (3.2%) compared to control subjects (0.2%). A significant increase in the size of the HTT CAG repeats was found in the AD compared to the control group, influenced by the presence of the Apoliprotein E (APOE)‐ℰ4 isoform. Post‐mortem assessments uncovered tauopathy pathology with positive polyglutamine aggregates, with a slight predominance in the neostriatum for PSP and CBD cases and somewhat greater limbic involvement in the AD case. Our results indicated a link between HTT CAG repeat expansion with other non‐HD pathology, suggesting they could share common neurodegenerative pathways. These findings support that genetic or histological screening for HTT repeat expansions should be considered in tauopathies. [ABSTRACT FROM AUTHOR]

The article discusses the long-term outcomes of deep brain stimulation (DBS) in a 10-year-old boy with Glutaric Aciduria Type 1 (GA1), a rare neurometabolic disorder. The boy experienced significant improvement in choreodystonic movements after DBS surgery, with some persistent symptoms in the left lower limb. DBS has shown effectiveness in treating drug-resistant movement disorders, but outcomes in pediatric patients with GA1 are still being studied due to limited evidence and heterogeneous results. Further research with larger patient cohorts is needed to better understand the impact of DBS on GA1 patients. [Extracted from the article]

Background: Previous studies suggest a link between CAG repeat number in the HTT gene and non-Huntington neurodegenerative diseases., Objective: The aim is to analyze whether expanded HTT CAG alleles and/or their size are associated with the risk for developing α-synucleinopathies or their behavior as modulators of the phenotype., Methods: We genotyped the HTT gene CAG repeat number and APOE-Ɛ isoforms in a case-control series including patients with either clinical or neuropathological diagnosis of α-synucleinopathy., Results: We identified three Parkinson's disease (PD) patients (0.30%) and two healthy controls (0.19%) carrying low-penetrance HTT repeat expansions whereas none of the dementia with Lewy bodies (DLB) or multisystem atrophy (MSA) patients carried pathogenic HTT expansions. In addition, a clear increase in the number of HTT CAG repeats was found among DLB and PD groups influenced by the male gender and also by the APOE4 allele among DLB patients. HTT intermediate alleles' (IAs) distribution frequency increased in the MSA group compared with controls (8.8% vs. 3.9%, respectively). These differences were indeed statistically significant in the MSA group with neuropathological confirmation. Two MSA HTT CAG IAs carriers with 32 HTT CAG repeats showed isolated polyQ inclusions in pons and basal nuclei, which are two critical structures in the neurodegeneration of MSA., Conclusions: Our results point to a link between HTT CAG number, HTT IAs, and expanded HTT CAG repeats with other non-HD brain pathology and support the hypothesis that they can share common neurodegenerative pathways. © 2022 International Parkinson and Movement Disorder Society., (© 2022 International Parkinson and Movement Disorder Society.)