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Borrone Dermato-Cardio-Skeletal (BDCS) syndrome is a severe progressive autosomal recessive disorder characterized by coarse facies, thick skin, acne conglobata, dysmorphic facies, vertebral abnormalities and mitral valve prolapse. We identified a consanguineous kindred with a child clinically diagnosed with BDCS. Linkage analysis of this family (BDCS1) identified five regions homozygous by descent with a maximum LOD score of 1.75. Linkage analysis of the family that originally defined BDCS (BDCS3) identified an overlapping linkage peak at chromosome 5q35.1. Sequence analysis identified two different homozygous mutations in BDCS1 and BDCS3, affecting the gene encoding the protein SH3 and PX domains 2B (SH3PXD2B), which localizes to 5q35.1. Western blot analysis of patient fibroblasts derived from affected individuals in both families demonstrated complete loss of SH3PXD2B. Homozygosity mapping and sequence analysis in a second published BDCS family (BDCS2) excluded SH3PXD2B. SH3PXD2B is required for the formation of functional podosomes, and loss-of-function mutations in SH3PXD2B have recently been shown to underlie 7 of 13 families with Frank-Ter Haar syndrome (FTHS). FTHS and BDCS share some overlapping clinical features; therefore, our results demonstrate that a proportion of BDCS and FTHS cases are allelic. Mutations in other gene(s) functioning in podosome formation and regulation are likely to underlie the SH3PXD2B-mutation-negative BDSC/FTHS patients. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Friedreich ataxia (FRDA) generally results from reduced frataxin, a mitochondrial protein involved in iron metabolism. We assessed whether HFE p.C282Y and/or p.H63D heterozygosity modifies age at disease onset or disease severity in individuals with FRDA. Methods One hundred seventy individuals with FRDA were assessed for the association of HFE p.C282Y and p.H63D with (1) age at disease onset and (2) Friedreich Ataxia Rating Scale (FARS) score. Results After adjusting for the smaller FXN GAA repeat size and sex, individuals with FRDA and heterozygous for p.C282Y had disease onset on average 3.72 years earlier than those homozygous for the wild-type amino acid ( P = 0.02). Neither mutation affected disease severity as measured by FARS. Conclusions It is hypothesized that the association between p.C282Y heterozygosity and an earlier age at FRDA onset relates to exacerbation of the already dysregulated iron metabolism that plays a major role in the pathogenesis of FRDA. © 2014 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Correction to: Environmental Science and Pollution Research https://doi.org/10.1007/s00109-02... The numbers 432 and 433 found in the 6th paragraph of the Discussion section is not included in this paper and should be removed. The original article can be found online at https://doi.org/10.1007/s00109-022-02188-1. Correction to: ASK1 is a novel molecular target for preventing aminoglycoside-induced hair cell death. [Extracted from the article]

Type II focal cortical dysplasia (FCD) is a neuropathological entity characterised by cortical dyslamination with the presence of dysmorphic neurons only (FCDIIA) or the presence of both dysmorphic neurons and balloon cells (FCDIIB). The year 2021 marks the 50th anniversary of the recognition of FCD as a cause of drug resistant epilepsy, and it is now the most common reason for epilepsy surgery. The causes of FCD remained unknown until relatively recently. The study of resected human FCD tissue using novel genomic technologies has led to remarkable advances in understanding the genetic basis of FCD. Mechanistic parallels have emerged between these non-neoplastic lesions and neoplastic disorders of cell growth and differentiation, especially through perturbations of the mammalian target of rapamycin (mTOR) signalling pathway. This narrative review presents the advances through which the aetiology of FCDII has been elucidated in chronological order, from recognition of an association between FCD and the mTOR pathway to the identification of somatic mosaicism within FCD tissue. We discuss the role of a two-hit mechanism, highlight current challenges and future directions in detecting somatic mosaicism in brain and discuss how knowledge of FCD may inform novel precision treatments of these focal epileptogenic malformations of human cortical development. [ABSTRACT FROM AUTHOR]

Objectives: Spinocerebellar ataxia 27B due to GAA repeat expansions in the fibroblast growth factor 14 (FGF14) gene has recently been recognized as a common cause of late‐onset hereditary cerebellar ataxia. Here we present the first report of this disease in the US population, characterizing its clinical manifestations, disease progression, pathological abnormalities, and response to 4‐aminopyridine in a cohort of 102 patients bearing GAA repeat expansions. Methods: We compiled a series of patients with SCA27B, recruited from 5 academic centers across the United States. Clinical manifestations and patient demographics were collected retrospectively from clinical records in an unblinded approach using a standardized form. Post‐mortem analysis was done on 4 brains of patients with genetically confirmed SCA27B. Results: In our cohort of 102 patients with SCA27B, we found that SCA27B was a late‐onset (57 ± 12.5 years) slowly progressive ataxia with an episodic component in 51% of patients. Balance and gait impairment were almost always present at disease onset. The principal finding on post‐mortem examination of 4 brain specimens was loss of Purkinje neurons that was most severe in the vermis most particularly in the anterior vermis. Similar to European populations, a high percent of patients 21/28 (75%) reported a positive treatment response with 4‐aminopyridine. Interpretation: Our study further estimates prevalence and further expands the clinical, imaging and pathological features of SCA27B, while looking at treatment response, disease progression, and survival in patients with this disease. Testing for SCA27B should be considered in all undiagnosed ataxia patients, especially those with episodic onset. ANN NEUROL 2024;96:1092–1103 [ABSTRACT FROM AUTHOR]

The document published in the Journal of Neurology discusses a case study of a 45-year-old male with Cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS). The patient presented with typical clinical features of CANVAS, including cognitive impairment, progressive imbalance, and sensory neuronopathy. Genetic analysis revealed a compound heterozygous copy number variant (CNV) and a pathogenic AAGGG(n) expansion in RFC1, expanding the understanding of the genetic mechanisms underlying CANVAS. The study highlights the importance of sequencing RFC1 in patients with a clinical diagnosis of CANVAS to identify potential genetic causes. [Extracted from the article]

Menkes disease is an X-linked copper deficiency disorder that results from mutations in the ATP7A(MNK) gene. A wide range of disease-causing mutations within ATP7A have been described, which lead to a diversity of phenotypes exhibited by Menkes patients. The mottled locus (Mo, Atp7a, Mnk) represents the murine homologue of the ATP7A gene, and the mottled mutants exhibit a diversity of phenotypes similar to that observed among Menkes patients. Therefore, these mutants are valuable models for studying Menkes disease. Two of the mottled mutants are brindled and blotchy and their phenotypes resemble classical Menkes disease and occipital horn syndrome (OHS) in humans, respectively. That is, the brindled mutant and patients with classical Menkes disease are severely copper deficient and have profound neurological problems, while OHS patients and the blotchy mouse have a much milder phenotype with predominantly connective tissue defects. In this study, in an attempt to understand the basis for the brindled and blotchy phenotypes, the copper transport characteristics and intracellular distribution of the Mnk protein were assessed in cultured cells from these mutants. The results demonstrated that the abnormal copper metabolism of brindled and blotchy cells may be related to a number of factors, which include the amount of Mnk protein, the intracellular location of the protein and the ability of Mnk to redistribute in elevated copper. The data also provide evidence for a relationship between the copper transport function and copper-dependent trafficking of Mnk. [ABSTRACT FROM AUTHOR]

The Menkes protein (MNK or ATP7A) is an important component of the mammalian copper transport pathway and is defective in Menkes disease, a fatal X-linked disorder of copper transport. To study the structure and function of this protein and to elucidate its role in cellular copper homeostasis, a cDNA construct encoding the full-length MNK protein was cloned into a mammalian expression vector under the control of the CMV promoter. Transfection of this plasmid construct into CHO-K1 cells yielded clones that expressed MNK at varying levels. Detailed characterization of four clones showed that an increase in MNK protein expression led to a corresponding increase in the level of copper resistance of the cells. Subcellular localization studies showed that in the parental CHO-K1 and the transfected cell lines, MNK was located in a post-Golgi compartment which, based on immunogold electron microscopic analyses, most likely represented the trans-Golgi network (TGN). When the extracellular copper concentration was increased, MNK in the clones as well as in CHO-K1 cells was redistributed to the cytoplasm and plasma membrane, but returned to the TGN under basal, low copper conditions. This report presents the first ultrastructural evidence for the association of MNK with vesicles within the cell and with the TGN and plasma membrane. It also demonstrates the stable expression of a functional MNK protein from a cDNA construct in mammalian cells, as well as the copper-induced redistribution of MNK in a cell line (CHO-K1) that was not selected for copper resistance or overexpression of MNK. [ABSTRACT FROM AUTHOR]

As a result, ddPCR has become a routine research genetic testing method for FCD samples collected from the Epilepsy Surgery Program at the Royal Children's Hospital, Melbourne. Previous studies showed that I MTOR i variants account for ~20-35% of FCD,[2],[[4], [6]] and the five most common I MTOR i variants constitute ~75% of all I MTOR i variants found in FCD (Supplementary Table 1). We read with interest the recent article by Pirozzi I et al. i [1] demonstrating the utility of droplet digital PCR (ddPCR) for the molecular genetic diagnosis of focal malformations of cortical development (FMCD) including focal cortical dysplasia (FCD), hemimegalencephaly (HMEG) and dysplastic megalencephaly (DMEG). This is an effective selection of probes to study DMEG, HMEG and FCD at the same time, resulting in a diagnostic rate of 24.2% for FCD and 81.8% for HMEG/DMEG. [Extracted from the article]

p38 mitogen-activated protein kinases (P38α and β) and c-Jun N-terminal kinases (JNK1, 2, and 3) are key mediators of the cellular stress response. However, prolonged P38 and JNK signalling is associated with damaging inflammatory responses, reactive oxygen species–induced cell death, and fibrosis in multiple tissues, such as the kidney, liver, central nervous system, and cardiopulmonary systems. These responses are associated with many human diseases, including arthritis, dementia, and multiple organ dysfunctions. Attempts to prevent P38- and JNK-mediated disease using small molecule inhibitors of P38 or JNK have generally been unsuccessful. However, apoptosis signal-regulating kinase 1 (ASK1), an upstream regulator of P38 and JNK, has emerged as an alternative drug target for limiting P38- and JNK-mediated disease. Within this review, we compile the evidence that ASK1 mediates damaging cellular responses via prolonged P38 or JNK activation. We discuss the potential benefits of ASK1 inhibition as a therapeutic and summarise the studies that have tested the effects of ASK1 inhibition in cell and animal disease models, in addition to human clinical trials for a variety of disorders. [ABSTRACT FROM AUTHOR]

Bottom-of-sulcus dysplasia (BOSD) is increasingly recognized as a cause of drug-resistant, surgically-remediable, focal epilepsy, often in seemingly MRI-negative patients. We describe the clinical manifestations, morphological features, localization patterns and genetics of BOSD, with the aims of improving management and understanding pathogenesis. We studied 85 patients with BOSD diagnosed between 2005–2022. Presenting seizure and EEG characteristics, clinical course, genetic findings and treatment response were obtained from medical records. MRI (3 T) and 18F-FDG-PET scans were reviewed systematically for BOSD morphology and metabolism. Histopathological analysis and tissue genetic testing were performed in 64 operated patients. BOSD locations were transposed to common imaging space to study anatomical location, functional network localization and relationship to normal MTOR gene expression. All patients presented with stereotyped focal seizures with rapidly escalating frequency, prompting hospitalization in 48%. Despite 42% patients having seizure remissions, usually with sodium channel blocking medications, most eventually became drug-resistant and underwent surgery (86% seizure-free). Prior developmental delay was uncommon but intellectual, language and executive dysfunction were present in 24%, 48% and 29% when assessed preoperatively, low intellect being associated with greater epilepsy duration. BOSDs were missed on initial MRI in 68%, being ultimately recognized following repeat MRI, 18F-FDG-PET or image postprocessing. MRI features were grey-white junction blurring (100%), cortical thickening (91%), transmantle band (62%), increased cortical T1 signal (46%) and increased subcortical FLAIR signal (26%). BOSD hypometabolism was present on 18F-FDG-PET in 99%. Additional areas of cortical malformation or grey matter heterotopia were present in eight patients. BOSDs predominated in frontal and pericentral cortex and related functional networks, mostly sparing temporal and occipital cortex, and limbic and visual networks. Genetic testing yielded pathogenic mTOR pathway variants in 63% patients, including somatic MTOR variants in 47% operated patients and germline DEPDC5 or NPRL3 variants in 73% patients with familial focal epilepsy. BOSDs tended to occur in regions where the healthy brain normally shows lower MTOR expression, suggesting these regions may be more vulnerable to upregulation of MTOR activity. Consistent with the existing literature, these results highlight (i) clinical features raising suspicion of BOSD; (ii) the role of somatic and germline mTOR pathway variants in patients with sporadic and familial focal epilepsy associated with BOSD; and (iii) the role of 18F-FDG-PET alongside high-field MRI in detecting subtle BOSD. The anatomical and functional distribution of BOSDs likely explain their seizure, EEG and cognitive manifestations and may relate to relative MTOR expression. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented discussing a study which aims to identify a novel RNF213 variant in a family with heterogeneous intracerebral vasculopathy.

This document discusses a study that explores two new repeat expansion disorders for late-onset cerebellar ataxia (CA) that are often accompanied by vestibulopathy and neuropathy. The study compares the severity of bilateral vestibulopathy (BV) in patients with RFC1 repeat expansions and FGF14 repeat expansions. The results show that BV is more severe in RFC1-expansion-positive patients compared to FGF14-expansion-positive patients. The study suggests that the severity of BV may help distinguish RFC1-positive individuals from other ataxic individuals, but further research is needed to investigate these findings due to limitations in the study. [Extracted from the article]

We examined more than 97,000 families from four neurodevelopmental disease cohorts and the UK Biobank to identify phenotypic and genetic patterns in parents contributing to neurodevelopmental disease risk in children. We identified within- and cross-disorder correlations between six phenotypes in parents and children, such as obsessive-compulsive disorder (R = 0.32–0.38, p < 10−126). We also found that measures of sub-clinical autism features in parents are associated with several autism severity measures in children, including biparental mean Social Responsiveness Scale scores and proband Repetitive Behaviors Scale scores (regression coefficient = 0.14, p = 3.38 × 10−4). We further describe patterns of phenotypic similarity between spouses, where spouses show correlations for six neurological and psychiatric phenotypes, including a within-disorder correlation for depression (R = 0.24–0.68, p < 0.001) and a cross-disorder correlation between anxiety and bipolar disorder (R = 0.09–0.22, p < 10−92). Using a simulated population, we also found that assortative mating can lead to increases in disease liability over generations and the appearance of "genetic anticipation" in families carrying rare variants. We identified several families in a neurodevelopmental disease cohort where the proband inherited multiple rare variants in disease-associated genes from each of their affected parents. We further identified parental relatedness as a risk factor for neurodevelopmental disorders through its inverse relationship with variant pathogenicity and propose that parental relatedness modulates disease risk by increasing genome-wide homozygosity in children (R = 0.05–0.26, p < 0.05). Our results highlight the utility of assessing parent phenotypes and genotypes toward predicting features in children who carry rare variably expressive variants and implicate assortative mating as a risk factor for increased disease severity in these families. [Display omitted] Many rare genetic variants are variably expressive, conferring risk for a range of clinical features with incomplete penetrance. We implicate assortative mating as a risk factor for disease in families carrying these variants by increasing genetic disease liability over generations, leading to the "genetic anticipation" observed in these families. [ABSTRACT FROM AUTHOR]

Objective: Friedreich ataxia (FRDA) is an inherited neurodegenerative disease characterized by ataxia and cardiomyopathy. Homozygous GAA trinucleotide repeat expansions in the first intron of FXN occur in 96% of affected individuals and reduce frataxin expression. Remaining individuals are compound heterozygous for a GAA expansion and a FXN point/insertion/deletion mutation. We examined disease-causing mutations and the impact on frataxin structure/function and clinical outcome in FRDA.Methods: We compared clinical information from 111 compound heterozygotes and 131 individuals with homozygous expansions. Frataxin mutations were examined using structural modeling, stability analyses and systematic literature review, and categorized into four groups: (1) homozygous expansions, and three compound heterozygote groups; (2) null (no frataxin produced); (3) moderate/strong impact; and (4) minimal impact. Mean age of onset and the presence of cardiomyopathy and diabetes mellitus were compared using regression analyses.Results: Mutations in the hydrophobic core of frataxin affected stability whereas surface residue mutations affected interactions with iron sulfur cluster assembly and heme biosynthetic proteins. The null group of compound heterozygotes had significantly earlier age of onset and increased diabetes mellitus, compared to the homozygous expansion group. There were no significant differences in mean age of onset between homozygotes and the minimal and moderate/strong impact groups.Interpretation: In compound heterozygotes, expression of partially functional mutant frataxin delays age of onset and reduces diabetes mellitus, compared to those with no frataxin expression from the non-expanded allele. This integrated analysis of categorized frataxin mutations and their correlation with clinical outcome provide a definitive resource for investigating disease pathogenesis in FRDA. [ABSTRACT FROM AUTHOR]

Objective: Favorable seizure outcome is reported following resection of bottom‐of‐sulcus dysplasia (BOSD). We assessed the distribution of epileptogenicity and dysplasia in and around BOSD to better understand this clinical outcome and the optimal surgical approach. Methods: We studied 27 children and adolescents with magnetic resonance imaging (MRI)‐positive BOSD who underwent epilepsy surgery; 85% became seizure‐free postresection (median = 5.0 years follow‐up). All patients had resection of the dysplastic sulcus, and 11 had additional resection of the gyral crown (GC) or adjacent gyri (AG). Markers of epileptogenicity were relative cortical hypometabolism on preoperative 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET), and spiking, ripples, fast ripples, spike–high‐frequency oscillation cross‐rate, and phase amplitude coupling (PAC) on preresection and postresection electrocorticography (ECoG), all analyzed at the bottom‐of‐sulcus (BOS), top‐of‐sulcus (TOS), GC, and AG. Markers of dysplasia were increased cortical thickness on preoperative MRI, and dysmorphic neuron density and variant allele frequency of somatic MTOR mutations in resected tissue, analyzed at similar locations. Results: Relative cortical metabolism was significantly reduced and ECoG markers were significantly increased at the BOS compared to other regions. Apart from spiking and PAC, which were greater at the TOS compared to the GC, there were no significant differences in PET and other ECoG markers between the TOS, GC, and AG, suggesting a cutoff of epileptogenicity at the TOS rather than a tapering gradient on the cortical surface. MRI and tissue markers of dysplasia were all maximal in the BOS, reduced in the TOS, and mostly absent in the GC. Spiking and PAC reduced significantly over the GC after resection of the dysplastic sulcus. Significance: These findings support the concept that dysplasia and intrinsic epileptogenicity are mostly limited to the dysplastic sulcus in BOSD and support resection or ablation confined to the MRI‐visible lesion as a first‐line surgical approach. 18F‐FDG PET and ECoG abnormalities in surrounding cortex seem to be secondary phenomena. [ABSTRACT FROM AUTHOR]

Mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE) is an important cause of drug-resistant epilepsy. A significant subset of individuals diagnosed with MOGHE display somatic mosaicism for loss-of-function variants in SLC35A2 , which encodes the UDP-galactose transporter. We developed a mouse model to investigate how disruption of this transporter leads to a malformation of cortical development. We used in utero electroporation and CRISPR/Cas9 to knockout Slc35a2 in a subset of layer 2/3 cortical neuronal progenitors in the developing brains of male and female fetal mice to model mosaic expression. Mosaic Slc35a2 knockout was verified through next-generation sequencing and immunohistochemistry of GFP-labelled transfected cells. Histology of brain tissue in mosaic Slc35a2 knockout mice revealed the presence of upper layer-derived cortical neurons in the white matter. Reconstruction of single filled neurons identified altered dendritic arborisation with Slc35a2 knockout neurons having increased complexity. Whole-cell electrophysiological recordings revealed that Slc35a2 knockout neurons display reduced action potential firing, increased afterhyperpolarisation duration and reduced burst-firing when compared with control neurons. Mosaic Slc35a2 knockout mice also exhibited significantly increased epileptiform spiking and increased locomotor activity. We successfully generated a mouse model of mosaic Slc35a2 deficiency, which recapitulates features of the human phenotype, including impaired neuronal migration. We show that knockout in layer 2/3 cortical neuron progenitors is sufficient to disrupt neuronal excitability, increase epileptiform activity and cause hyperactivity in mosaic mice. Our mouse model provides an opportunity to further investigate the disease mechanisms that contribute to MOGHE and facilitate the development of precision therapies. • A mouse model of MOGHE was generated by cortical mosaic Slc35a2 knockout. • Slc35a2 mosaicism causes increased network-level epileptiform activity. • Excitatory neuron dendritic arborisation is altered by Slc35a2 knockout. • Electrophysiological recordings from knockout neurons reveal decreased excitability. [ABSTRACT FROM AUTHOR]

Abstract: PArkin Co-Regulated Gene is a gene that shares a bidirectional promoter with the Parkinson''s disease associated gene parkin. The encoded protein (PACRG) is found in Lewy bodies and glial cytoplasmic inclusions, the pathological hallmarks of parkinsonian disorders. To investigate the function and regulation of PACRG, cells were treated with the proteasomal inhibitor, MG-132. As previously reported with parkin, inhibition of the proteasome resulted in the formation of aggresomes that contained endogenous PACRG. Increased levels of exogenous PACRG resulted in an increase in aggresome formation, and conferred significant resistance to aggresome disruption and cell death mediated by microtubule depolymerisation. In contrast, shRNA mediated knockdown of PACRG significantly reduced aggresome numbers. Elevated levels of PACRG also resulted in increased autophagy, as demonstrated by biochemical and quantitative analysis of autophagic vesicles, whereas lowered levels of PACRG resulted in reduced autophagy. These results suggest a role for PACRG in aggresome formation and establish a further link between the UPS and autophagy. [Copyright &y& Elsevier]

Abstract: Mutation of the parkin gene (parkin) is the most common cause of early-onset Parkinson’s disease and to date over 100 different mutations have been described. However, screening of parkin is complicated by its genomic architecture and context. Notably, dosage alterations in parkin account for greater than 50% of mutations detected in some cohort studies. To improve the accuracy and reproducibility of parkin genomic dosage assays we have identified and analysed cell lines with chromosomal abnormalities affecting 6q26. FISH and real-time PCR analysis identified cell lines with reduced or increased copy number spanning the entire parkin locus. These cell lines represent a valuable resource to facilitate accurate copy number determination of any parkin exon. The reagents are easily obtainable and are compatible with current quantitative technologies and platforms. [Copyright &y& Elsevier]

Aminoglycoside antibiotics are lifesaving medicines, crucial for the treatment of chronic or drug resistant infections. However, aminoglycosides are toxic to the sensory hair cells in the inner ear. As a result, aminoglycoside-treated individuals can develop permanent hearing loss and vestibular impairment. There is considerable evidence that reactive oxygen species (ROS) production and the subsequent phosphorylation of c-Jun N-terminal kinase (JNK) and P38 mitogen-activated protein kinase (P38) drives apoptosis in aminoglycoside-treated hair cells. However, treatment strategies that directly inhibit ROS, JNK, or P38 are limited by the importance of these molecules for normal cellular function. Alternatively, the upstream regulator apoptosis signal-regulating kinase 1 (ASK1/MAP3K5) is a key mediator of ROS-induced JNK and P38 activation under pathologic but not homeostatic conditions. We investigated ASK1 as a mediator of drug-induced hair cell death using cochlear explants from Ask1 knockout mice, demonstrating that Ask1 deficiency attenuates neomycin-induced hair cell death. We then evaluated pharmacological inhibition of ASK1 with GS-444217 as a potential otoprotective therapy. GS-444217 significantly attenuated hair cell death in neomycin-treated explants but did not impact aminoglycoside efficacy against P. aeruginosa in the broth dilution test. Overall, we provide significant pre-clinical evidence that ASK1 inhibition represents a novel strategy for preventing aminoglycoside ototoxicity. Key messages: ASK1 is an upstream, redox-sensitive regulator of P38 and JNK, which are known mediators of hair cell death. Ask1 knockout does not affect hair cell development in vivo, but significantly reduces aminoglycoside-induced hair cell death in vitro. A small-molecule inhibitor of ASK1 attenuates neomycin-induced hair cell death, and does not impact antibiotic efficacy in vitro. ASK1 may be a novel molecular target for preventing aminoglycoside-induced hearing loss. [ABSTRACT FROM AUTHOR]

Purpose: The complexity and severity of rare genetic conditions pose substantial burden to families. While the importance of spillovers on carers' health in resource allocation decisions is increasingly recognised, there is significant lack of empirical evidence in the context of rare diseases. The objective of this study was to estimate the health spillovers of paediatric rare genetic conditions on parents. Methods: Health-related quality-of-life (HRQoL) data from children with rare genetic conditions (genetic kidney diseases, mitochondrial diseases, epileptic encephalopathies, brain malformations) and their parents were collected using the CHU9D and SF-12 measures, respectively. We used two approaches to estimate parental health spillovers. To quantify the 'absolute health spillover', we matched our parent cohort to the Australian general population. To quantify the 'relative health spillover', regression models were applied using the cohort data. Results: Parents of affected children had significantly lower HRQoL compared to matched parents in the general public (− 0.06; 95% CIs − 0.08, − 0.04). Multivariable regression demonstrated a positive association between parental and child health. The mean magnitude of HRQoL loss in parents was estimated to be 33% of the HRQoL loss observed in children (95% CIs 21%, 46%). Conclusion: Paediatric rare genetic conditions appear to be associated with substantial parental health spillovers. This highlights the importance of including health effects on family members and caregivers into economic evaluation of genomic technologies and personalised medicine. Overlooking spillover effects may undervalue the benefits of diagnosis and management in this context. This study also expands the knowledge of family spillover to the rare disease spectrum. [ABSTRACT FROM AUTHOR]

Pathogenic variants in the gene encoding the small GTPase Ras analogue in Brain 39b (RAB39B) are associated with early-onset parkinsonism. In this study we investigated the expression and localization of RAB39B (RNA and protein) in mouse brain tissue to gain a better understanding of its normal physiological function(s) and role in disease. We developed novel resources, including monoclonal antibodies directed against RAB39B and mice with Rab39b knockout, and performed real-time PCR and western blot analysis on whole brain lysates. To determine the spatial localization of Rab39b RNA and protein, we performed in-situ hybridization and immunohistochemistry on fresh frozen and fixed brain tissue. Our results show that RAB39B is localized throughout the cortex, hippocampus and substantia nigra of mice throughout postnatal life. We found high levels of RAB39B within MAP2 positive cortical and hippocampal neurons, and TH positive dopaminergic neurons in the substantia nigra pars compacta. Our studies support and extend current knowledge of the localization of RAB39B. We validate RAB39B as a neuron-enriched protein and demonstrate that it is present throughout the mouse cortex and hippocampus. Further, we observe high levels in the substantia nigra pars compacta, the brain region most affected in Parkinson's disease pathology. The distribution of Rab39b is consistent with human disease associations with parkinsonism and cognitive impairment. We also describe and validate novel resources, including monoclonal antibodies directed against RAB39B and mice with Rab39b knockout, both of which are valuable tools for future studies of the molecular function of RAB39B. [ABSTRACT FROM AUTHOR]

The Mendelian disorders of chromatin machinery (MDCMs) represent a distinct subgroup of disorders that present with neurodevelopmental disability. The chromatin machinery regulates gene expression by a range of mechanisms, including by post-translational modification of histones, responding to histone marks, and remodelling nucleosomes. Some of the MDCMs that impact on histone modification may have potential therapeutic interventions. Two potential treatment strategies are to enhance the intracellular pool of metabolites that can act as substrates for histone modifiers and the use of medications that may inhibit or promote the modification of histone residues to influence gene expression. In this article we discuss the influence and potential treatments of histone modifications involving histone acetylation and histone methylation. Genomic technologies are facilitating earlier diagnosis of many Mendelian disorders, providing potential opportunities for early treatment from infancy. This has parallels with how inborn errors of metabolism have been afforded early treatment with newborn screening. Before this promise can be fulfilled, we require greater understanding of the biochemical fingerprint of these conditions, which may provide opportunities to supplement metabolites that can act as substrates for chromatin modifying enzymes. Importantly, understanding the metabolomic profile of affected individuals may also provide disorder-specific biomarkers that will be critical for demonstrating efficacy of treatment, as treatment response may not be able to be accurately assessed by clinical measures. [ABSTRACT FROM AUTHOR]

Background: Intraoperative awareness with recall while under apparently adequate general anesthesia is a rare, unexplained, and often very distressing phenomenon. It is possible that a relatively small number of genetic variants might underlie the failure of general anesthetic drugs to adequately suppress explicit memory formation and recall in the presence of apparently adequate anesthesia concentrations.Methods: The authors recruited 12 adult patients who had experienced an episode of intraoperative awareness with recall (compared with 12 controls), performed whole exome sequencing, and applied filtering to obtain a set of genetic variants that might be associated with intraoperative awareness with recall. The criteria were that the variant (1) had a minor allele frequency less than 0.1% in population databases, (2) was within exonic or splicing regions, (3) caused a nonsynonymous change, (4) was predicted to be functionally damaging, (5) was expressed in the top 50% of genes expressed in the brain, and (6) was within genes in Kyoto Encyclopedia of Genes and Genomes pathways associated with general anesthesia, drug metabolism, arousal, and memory.Results: The authors identified 29 rare genetic variants in 27 genes that were absent in controls and could plausibly be associated with this disorder. One variant in CACNA1A was identified in two patients and two different variants were identified in both CACNA1A and CACNA1S. Of interest was the relative overrepresentation of variants in genes encoding calcium channels and purinergic receptors.Conclusions: Within the constraints of the filtering process used, the authors did not find any single gene variant or gene that was strongly associated with intraoperative awareness with recall. The authors report 27 candidate genes and associated pathways identified in this pilot project as targets of interest for future larger biologic and epidemiologic studies. [ABSTRACT FROM AUTHOR]

Repeat expansions cause more than 30 inherited disorders, predominantly neurogenetic. These can present with overlapping clinical phenotypes, making molecular diagnosis challenging. Single-gene or small-panel PCR-based methods can help to identify the precise genetic cause, but they can be slow and costly and often yield no result. Researchers are increasingly performing genomic analysis via whole-exome and whole-genome sequencing (WES and WGS) to diagnose genetic disorders. However, until recently, analysis protocols could not identify repeat expansions in these datasets. We developed exSTRa (expanded short tandem repeat algorithm), a method that uses either WES or WGS to identify repeat expansions. Performance of exSTRa was assessed in a simulation study. In addition, four retrospective cohorts of individuals with eleven different known repeat-expansion disorders were analyzed with exSTRa. We assessed results by comparing the findings to known disease status. Performance was also compared to three other analysis methods (ExpansionHunter, STRetch, and TREDPARSE), which were developed specifically for WGS data. Expansions in the assessed STR loci were successfully identified in WES and WGS datasets by all four methods with high specificity and sensitivity. Overall, exSTRa demonstrated more robust and superior performance for WES data than did the other three methods. We demonstrate that exSTRa can be effectively utilized as a screening tool for detecting repeat expansions in WES and WGS data, although the best performance would be produced by consensus calling, wherein at least two out of the four currently available screening methods call an expansion. [ABSTRACT FROM AUTHOR]

Mutations in DEPDC5 and NPRL3 subunits of GATOR1, a modulator of mechanistic target of rapamycin (mTOR), are linked to malformations of cortical development (MCD). Brain specimens from these individuals reveal abnormal cortical lamination, altered cell morphology, and hyperphosphorylation of ribosomal S6 protein (PS6), a marker for mTOR activation. While numerous studies have examined GATOR1 subunit function in non-neuronal cell lines, few have directly assessed loss of GATOR1 subunit function in neuronal cell types. We hypothesized that DEPDC5 or NPRL3 shRNA-mediated knockdown ( DEPDC5/NPRL3 KD) leads to inappropriate functional activation of mTOR and mTOR-dependent alterations in neuronal morphology. Neuronal size was determined in human specimens harboring DEPDC5 or NPRL3 mutations resected for epilepsy treatment. DEPDC5/NPRL3 KD effects on cell size, filopodial extension, subcellular mTOR complex 1 (mTORC1) localization, and mTORC1 activation during nutrient deprivation were assayed in mouse neuroblastoma cells (N2aC) and mouse subventricular zone derived neural progenitor cells (mNPCs). mTORC1-dependent effects of DEPDC5/NPRL3 KD were determined using the mTOR inhibitor rapamycin. Changes in mTOR subcellular localization and mTORC1 pathway activation following DEPDC5/NPRL3 KD were determined by examining the proximity of mTOR to the lysosomal surface during amino acid starvation. Neurons exhibiting PS6 immunoreactivity (Ser 235/236) in human specimens were 1.5× larger than neurons in post-mortem control samples. DEPDC5/NPRL3 KD caused mTORC1, but not mTORC2, hyperactivation, soma enlargement, and increased filopodia in N2aC and mNPCs compared with wildtype cells. DEPDC5/NPRL3 KD led to inappropriate mTOR localization at the lysosome along with constitutive mTOR activation following amino acid deprivation. DEPDC5/NPRL3 KD effects on morphology and functional mTOR activation were reversed by rapamycin. mTOR-dependent effects of DEPDC5/NPRL3 KD on morphology and subcellular localization of mTOR in neurons suggests that loss-of-function in GATOR1 subunits may play a role in MCD formation during fetal brain development. [ABSTRACT FROM AUTHOR]

The identification of pathogenic mutations in Ras analog in brain 39B (RAB39B) and Ras analog in brain 32 (RAB32) that cause Parkinson's disease (PD) has highlighted the emerging role of protein trafficking in disease pathogenesis. Ras analog in brain (Rab) Guanosine triphosphatase (GTPase) function as master regulators of membrane trafficking, including vesicle formation, movement along cytoskeletal networks, and membrane fusion. Recent studies have linked Rab GTPases with α-synuclein, Leucine-rich repeat kinase 2, and Vacuolar protein sorting 35, 3 key proteins in PD pathogenesis. In this review, we discuss the various RAB GTPases associated with PD, current progress in the research, and potential future directions. Investigations into the function of RAB GTPases will likely provide significant insight into the etiology of PD and identify novel therapeutic targets for a currently incurable disease. © 2018 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

We describe first cousin sibling pairs with focal epilepsy, one of each pair having focal cortical dysplasia (FCD) IIa. Linkage analysis and whole-exome sequencing identified a heterozygous germline frameshift mutation in the gene encoding nitrogen permease regulator-like 3 (NPRL3). NPRL3 is a component of GAP Activity Towards Rags 1, a negative regulator of the mammalian target of rapamycin complex 1 signaling pathway. Immunostaining of resected brain tissue demonstrated mammalian target of rapamycin activation. Screening of 52 unrelated individuals with FCD identified 2 additional patients with FCDIIa and germline NPRL3 mutations. Similar to DEPDC5, NPRL3 mutations may be considered as causal variants in patients with FCD or magnetic resonance imaging-negative focal epilepsy. [ABSTRACT FROM AUTHOR]

Objective: To investigate the potential role of PArkin co-regulated gene (PACRG) in human male infertility. Design: Case-control study. Setting: Academic reproductive biology department. Patient(s): Blood samples were obtained from 610 patients and 156 normal control subjects. Intervention(s): Genomic DNA was used as template for polymerase chain reaction amplification of the PACRG promoter and coding exons. The amplified fragments were tested for DNA sequence variations by direct sequencing and restriction enzyme analysis. Main Outcome Measure(s): Gene structure and sequence alterations of PACRG in infertile male patients. Result(s): The structure of PACRG was determined to comprise 5 coding exons, generating a single transcript in the testis which encoded a predicted protein of 257 amino acids. No pathogenic mutations were identified; however, a variant in the promoter of PACRG was shown to be significantly associated with azoospermia, but not oligospermia, in the case-control cohort. Conclusion(s): Mutation of PACRG was not identified as a cause of male infertility, but variation in the promoter was demonstrated to be a risk factor associated with azoospermia. [Copyright &y& Elsevier]

Abstract: PArkin Co-Regulated Gene (PACRG) is a novel gene which is transcriptionally co-regulated with the parkin gene (PRKN) by a shared bi-directional promoter. To determine whether mutations in PACRG are associated with early-onset Parkinson''s disease (EO-PD), we performed sequence and dosage analysis of 76 EO-PD patients from a Taiwanese–Ethnic Chinese cohort. This analysis identified two novel nucleotide variants in the non-coding region of PACRG. One patient had an IVS2+247851T>C heterozygous change and two patients had an IVS4+78A>G heterozygous alteration. Neither of these variants was present in the 91 controls tested. A third intronic polymorphism (IVS1+85744insC) was present in cases and controls at an equivalent frequency (∼0.25). To facilitate gene dosage analysis, we identified cell lines with a heterozygous deletion or duplication of the entire PACRG locus. Three patients with heterozygous dosage alterations were identified, including two patients with an exon 2 duplication and one patient with an exon 3 deletion of PACRG. No dosage alterations were observed in the 91 controls analyzed (χ 2 =3.66, P =0.056). Our results suggest that point mutations in PACRG are not a common cause of EO-PD but haploinsufficiency for PACRG may be associated with disease. [Copyright &y& Elsevier]

Abstract: Parkin Co-Regulated Gene (PACRG) is a novel gene that is oriented in a head-to-head array with parkin, and expression of the two genes is regulated by a shared bi-directional promoter. Mutations in parkin are the most common cause of early-onset autosomal recessive Parkinson''s disease, however the function of PACRG and potential role in the pathogenesis of Parkinson''s disease are unclear. We generated polyclonal anti-PACRG antisera and performed immunohistochemical analysis of the regional and temporal distribution of Pacrg in the mouse brain. The protein was heterogeneously expressed in neurons throughout the mouse brain, with highest levels observed in the rhombencephalon and mesencephalon. Expression was detectable at 1 week of age, increased to maximal levels by 4 weeks and subsequently declined after 3 months. Comparison of parkin and Pacrg immunohistochemistry demonstrated a correlation of both staining distribution and intensity for the two proteins. These results suggest that the transcriptional co-regulation of Pacrg and parkin leads to a similar regional protein distribution in mouse brain, which may have functional significance for the two proteins. [Copyright &y& Elsevier]

• RResection of cortex in the center of tubers was sufficient to control focal motor seizures in 4 operated children (5 surgeries) with TSC. • The finding supports our previous observations of seizure activity on ECoG and dysplasia on MRI being maximal in the center of epileptotogenic tubers. • Dysmorphic neurons were abundant in tuber centers, supporting previous reports of dysmorphic neurons being the epileptogenic cell line in TSC. Our previous studies suggest the tuber center is the seizure focus in tuberous sclerosis complex (TSC). We report findings from 5 epilepsy surgeries in 4 children with TSC and focal motor seizures from single tubers in primary sensorimotor cortex in which resection was limited to the cortex in the tuber center. Intraoperative electrocorticography showed epileptiform activity in the tuber center, with or without propagation to the tuber rim and surrounding perituberal cortex. Histopathology showed an abundance of dysmorphic neurons in the tuber center compared to the rim in four paired specimens, dysmorphic neurons being the reported epileptogenic cell line in TSC. Associated focal motor seizures were eliminated in all children (mean follow up 6.3 years) without postoperative deficits. Tuber center resections are a potential alternative to complete tuberectomy in patients with epileptogenic tubers in eloquent cortex and potentially also in children with a high tuber load and multifocal seizures. [ABSTRACT FROM AUTHOR]

We present the case of a male infant with bilateral perisylvian polymicrogyria associated with a de novo duplication of chromosome region 17p13.3p13.2. To our knowledge, this is the first report of polymicrogyria associated with the 17p13.3 contiguous gene duplication syndrome. Testing for known monogenic causes of polymicrogyria was negative and there was no clinical evidence of an acquired prenatal cause. Given the critical, dose-sensitive role that the 17p13.3 region plays in brain development, we suggest that the chromosome duplication is the most likely explanation for the polymicrogyria. Clinical and functional studies have demonstrated deleterious effects of increased LIS1 expression on the developing brain and the contribution of YWHAE to the brain phenotype of the 17p13 duplication syndrome. There is also evidence that CRK , the other candidate gene in this region, via interaction with LIS1, plays a critical role in cortical development. In addition to LIS1 , YWHAE and CRK , our patient's chromosome duplication involves at least 100 other genes, less than half of which are annotated at the time of writing. It is expected that the ongoing use of chromosome microarray and next-generation sequencing to investigate the genetic causes of brain malformations will continue to extend our understanding of the 17p13 region and of the contributions of the genes in this region to cortical development. [ABSTRACT FROM AUTHOR]

Infantile epileptic spasms syndrome is a severe epilepsy of infancy that is often associated with focal malformations of cortical development. This study aimed to elucidate the genetic landscape and histopathologic aetiologies of infantile epileptic spasms syndrome due to focal malformations of cortical development requiring surgery. Fifty-nine children with a history of infantile epileptic spasms syndrome and focal malformations of cortical development on MRI were studied. Genetic testing of resected brain tissue was performed by high-coverage targeted panel sequencing or exome sequencing. Histopathology and MRI were reviewed, and integrated clinico-pathological diagnoses were established. A genetic diagnosis was achieved in 47 children (80% of cohort). Germline pathogenic variants were identified in 27/59 (46%) children, in TSC2 (x19), DEPDC5 (x2), CDKL5 (x2), NPRL3 (x1), FGFR1 (x1), TSC1 (x1), and one child with both a TUBB2A / TUBB2B deletion and a pathogenic variant in COL4A1 (x1). Pathogenic brain somatic variants were identified in 21/59 (36%) children, in SLC35A2 (x9), PIK3CA (x3), AKT3 (x2), TSC2 (x2), MTOR (x2), OFD1 (x1), TSC1 (x1) and DEPDC5 (x1). One child had 'two-hit' diagnosis, with both germline and somatic pathogenic DEPDC5 variants in trans. Multimodal data integration resulted in clinical diagnostic reclassifications in 24% of children, emphasizing the importance of combining genetic, histopathologic and imaging findings. Mammalian target of rapamycin pathway variants were identified in most children with tuberous sclerosis or focal cortical dysplasia type II. All nine children with somatic SLC35A2 variants in brain were reclassified to mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy. Somatic mosaicism was a major cause of focal cortical dysplasia type II/hemimegalencephaly (81%) and mild malformation of cortical development with oligodendroglial hyperplasia (100%). The genetic landscape of infantile epileptic spasms syndrome due to focal malformations comprises germline and somatic variants in a range of genes, with mTORopathies and SLC35A2 -related mild malformation of cortical development with oligodendroglial hyperplasia being the major causes. Multimodal data integration incorporating genetic data aids in optimizing diagnostic pathways and can guide surgical decision-making and inform future research and therapeutic interventions., Competing Interests: K.B.H. has received project funding (for unrelated work) from Praxis Precision Medicines, RogCon, Inc, and UCB Australia. The remaining authors report no disclosures., (© The Author(s) 2025. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Background/objectives: Dysregulation of molecular pathways associated with mechanistic target of rapamycin (mTOR) and elevated rates of neurodevelopmental disorders are implicated in the genetic syndromes neurofibromatosis type 1 (NF1), tuberous sclerosis complex (TSC), fragile X syndrome (FXS), and Noonan syndrome (NS). Given shared molecular and clinical features, understanding convergent and divergent implications of these syndromes on brain development may offer unique insights into disease mechanisms. While an increasing number of studies have examined brain volumes in these syndromes, the effects of each syndrome on global and subcortical brain volumes are unclear. Therefore, the aim of the current study was to conduct a systematic review and meta-analysis to synthesize existing literature on volumetric brain changes across TSC, FXS, NF1, and NS. Study outcomes were the effect sizes of the genetic syndromes on whole brain, gray and white matter, and subcortical volumes compared to typically developing controls., Subjects/methods: We performed a series of meta-analyses synthesizing data from 23 studies in NF1, TSC, FXS, and NS (pooled N = 1556) reporting whole brain volume, gray and white matter volumes, and volumes of subcortical structures compared to controls., Results: Meta-analyses revealed significantly larger whole brain volume, gray and white matter volumes, and subcortical volumes in NF1 compared to controls. FXS was associated with increased whole brain, and gray and white matter volumes relative to controls, but effect sizes were smaller than those seen in NF1. In contrast, studies in NS indicated smaller whole brain and gray matter volumes, and reduced subcortical volumes compared to controls. For individuals with TSC, there were no significant differences in whole brain, gray matter, and white volumes compared to controls. Volumetric effect sizes were not moderated by age, sex, or full-scale IQ., Conclusions: This meta-analysis revealed that dysregulation of mTOR signaling across pre- and post-natal periods of development can result in convergent and divergent consequences for brain volume among genetic syndromes. Further research employing advanced disease modeling techniques with human pluripotent stem cell-derived in vitro models is needed to further refine our understanding of between and within syndrome variability on early brain development and identify shared molecular mechanisms for the development of pharmaceutical interventions., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Repeat expansions in FGF14 cause autosomal dominant late-onset cerebellar ataxia (SCA27B) with estimated pathogenic thresholds of 250 (incomplete penetrance) and 300 AAG repeats (full penetrance), but the sequence of pathogenic and non-pathogenic expansions remains unexplored. Here, we demonstrate that STRling and ExpansionHunter accurately detect FGF14 expansions from short-read genome data using outlier approaches. By combining long-range PCR and nanopore sequencing in 169 patients with cerebellar ataxia and 802 controls, we compare FGF14 expansion alleles, including interruptions and flanking regions. Uninterrupted AAG expansions are significantly enriched in patients with ataxia from a lower threshold (180-200 repeats) than previously reported based on expansion size alone. Conversely, AAGGAG hexameric expansions are equally frequent in patients and controls. Distinct 5' flanking regions, interruptions and pre-repeat sequences correlate with repeat size. Furthermore, pure AAG (pathogenic) and AAGGAG (non-pathogenic) repeats form different secondary structures. Regardless of expansion size, SCA27B is a recognizable clinical entity characterized by frequent episodic ataxia and downbeat nystagmus, similar to the presentation observed in a family with a previously unreported nonsense variant (SCA27A). Overall, this study suggests that SCA27B is a major overlooked cause of adult-onset ataxia, accounting for 23-31% of unsolved patients. We strongly recommend re-evaluating pathogenic thresholds and integrating expansion sequencing into the molecular diagnostic process., (© 2024. The Author(s).)

Variable expressivity of disease-associated variants implies a role for secondary variants that modify clinical features. We assessed the effects of modifier variants towards clinical outcomes of 2,252 individuals with primary variants. Among 132 families with the 16p12.1 deletion, distinct rare and common variant classes conferred risk for specific developmental features, including short tandem repeats for neurological defects and SNVs for microcephaly, while additional disease-associated variants conferred multiple genetic diagnoses. Within disease and population cohorts of 773 individuals with the 16p12.1 deletion, we found opposing effects of secondary variants towards clinical features across ascertainments. Additional analysis of 1,479 probands with other primary variants, such as 16p11.2 deletion and CHD8 variants, and 1,084 without primary variants, showed that phenotypic associations differed by primary variant context and were influenced by synergistic interactions between primary and secondary variants. Our study provides a paradigm to dissect the genomic architecture of complex disorders towards personalized treatment., Competing Interests: DECLARATION OF INTERESTS The authors declare no competing interests.

Around 60% of individuals with neurodevelopmental disorders (NDD) remain undiagnosed after comprehensive genetic testing, primarily of protein-coding genes 1 . Large genome-sequenced cohorts are improving our ability to discover new diagnoses in the non-coding genome. Here we identify the non-coding RNA RNU4-2 as a syndromic NDD gene. RNU4-2 encodes the U4 small nuclear RNA (snRNA), which is a critical component of the U4/U6.U5 tri-snRNP complex of the major spliceosome 2 . We identify an 18 base pair region of RNU4-2 mapping to two structural elements in the U4/U6 snRNA duplex (the T-loop and stem III) that is severely depleted of variation in the general population, but in which we identify heterozygous variants in 115 individuals with NDD. Most individuals (77.4%) have the same highly recurrent single base insertion (n.64&#95;65insT). In 54 individuals in whom it could be determined, the de novo variants were all on the maternal allele. We demonstrate that RNU4-2 is highly expressed in the developing human brain, in contrast to RNU4-1 and other U4 homologues. Using RNA sequencing, we show how 5' splice-site use is systematically disrupted in individuals with RNU4-2 variants, consistent with the known role of this region during spliceosome activation. Finally, we estimate that variants in this 18 base pair region explain 0.4% of individuals with NDD. This work underscores the importance of non-coding genes in rare disorders and will provide a diagnosis to thousands of individuals with NDD worldwide., (© 2024. The Author(s).)