PSMD11 loss-of-function variants correlate with a neurobehavioral phenotype, obesity, and increased interferon response.

Primary proteasomopathies have recently emerged as a new class of rare early-onset neurodevelopmental disorders (NDDs) caused by pathogenic variants in the PSMB1, PSMC1, PSMC3, or PSMD12 proteasome genes. Proteasomes are large multi-subunit protein complexes that maintain cellular protein homeostasis by clearing ubiquitin-tagged damaged, misfolded, or unnecessary proteins. In this study, we have identified PSMD11 as an additional proteasome gene in which pathogenic variation is associated with an NDD-causing proteasomopathy. PSMD11 loss-of-function variants caused early-onset syndromic intellectual disability and neurodevelopmental delay with recurrent obesity in 10 unrelated children. Our findings demonstrate that the cognitive impairment observed in these individuals could be recapitulated in Drosophila melanogaster with depletion of the PMSD11 ortholog Rpn6, which compromised reversal learning. Our investigations in subject samples further revealed that PSMD11 loss of function resulted in impaired 26S proteasome assembly and the acquisition of a persistent type I interferon (IFN) gene signature, mediated by the integrated stress response (ISR) protein kinase R (PKR). In summary, these data identify PSMD11 as an additional member of the growing family of genes associated with neurodevelopmental proteasomopathies and provide insights into proteasomal biology in human health.

Biallelic variation in the choline and ethanolamine transporter FLVCR1 underlies a pleiotropic disease spectrum from adult neurodegeneration to severe developmental disorders.

FLVCR1 encodes Feline leukemia virus subgroup C receptor 1 (FLVCR1), a solute carrier (SLC) transporter within the Major Facilitator Superfamily. FLVCR1 is a widely expressed transmembrane protein with plasma membrane and mitochondrial isoforms implicated in heme, choline, and ethanolamine transport. While Flvcr1 knockout mice die in utero with skeletal malformations and defective erythropoiesis reminiscent of Diamond-Blackfan anemia, rare biallelic pathogenic FLVCR1 variants are linked to childhood or adult-onset neurodegeneration of the retina, spinal cord, and peripheral nervous system. We ascertained from research and clinical exome sequencing 27 individuals from 20 unrelated families with biallelic ultra-rare missense and predicted loss-of-function (pLoF) FLVCR1 variant alleles. We characterize an expansive FLVCR1 phenotypic spectrum ranging from adult-onset retinitis pigmentosa to severe developmental disorders with microcephaly, reduced brain volume, epilepsy, spasticity, and premature death. The most severely affected individuals, including three individuals with homozygous pLoF variants, share traits with Flvcr1 knockout mice and Diamond-Blackfan anemia including macrocytic anemia and congenital skeletal malformations. Pathogenic FLVCR1 missense variants primarily lie within transmembrane domains and reduce choline and ethanolamine transport activity compared with wild-type FLVCR1 with minimal impact on FLVCR1 stability or subcellular localization. Several variants disrupt splicing in a mini-gene assay which may contribute to genotype-phenotype correlations. Taken together, these data support an allele-specific gene dosage model in which phenotypic severity reflects residual FLVCR1 activity. This study expands our understanding of Mendelian disorders of choline and ethanolamine transport and demonstrates the importance of choline and ethanolamine in neurodevelopment and neuronal homeostasis.

Botulinum Toxin Type A for the Treatment of Limb Myokymia: Experiences of Three Children.

Myokymia is a rare neuromuscular disorder and limb involvement is not common in this disease. To the best of our knowledge, isolated peroneus longus muscle myokymia was not reported before in the literature; and for that reason treatment protocols were not established. Botulinum toxin type A (BoNT-A), which is used in the treatment of a variety of neurologic disorders, was also defined as a treatment option in myokymia. Herein, we will report three cases of peroneus longus muscle myokymia in children in the absence of any other neurological findings, and the successful results of treatment with local BoNT-A injections. BoNT-A is a safe and effective treatment in myokymia when administered by an experienced clinician and should always be considered when the disorder is persistent and affecting the life of the patient.

Evaluation of hair structural abnormalities in children with different neurological diseases.

BACKGROUND: Hair microscopy is a fast and effortless diagnostic method for many diseases affecting hair in daily practice. Many diseases can present with hair shaft disorders in pediatric neurology practice. METHODS: Children with pathological hair findings were included in our study. Microscopic evaluation of the hair was performed under light microscopy. The clinical findings, pathological hair shaft findings, laboratory tests, and final diagnosis of the patients were evaluated. RESULTS: In our study, 16 patients with rare pathological hair findings were identified. Of these 16 patients, nine were diagnosed with giant axonal neuropathy, three with Griscelli syndrome, two with Menkes disease, and two with autosomal recessive woolly hair disease. In hair inspection, curly and tangled hair in patients with giant axonal neuropathy; silvery blond hair in patients with Griscelli syndrome; sparse, coarse, and light-colored hair in patients with Menkes disease; and hypotrichosis in patients with autosomal recessive woolly hair were remarkable findings. Dystrophic hair was detected in most of the patients on light microscopy. In addition, signs of trichorrhexis nodosa, tricoptylosis, and pili torti were found. In particular, pigment deposition in the hair shaft of two patients diagnosed with Griscelli syndrome and pili torti findings in two patients with Menkes disease were the most important findings suggestingthe diagnosis. CONCLUSIONS: Detection of hair findings in the physical examination and performing light microscopic evaluation facilitates the diagnosis of rare diseases accompanied by hair findings. A hair examination should be performed as a part of physical and neurological examinationson eachpatient regardless of thecomplaint.

Neurodevelopmental disorder with microcephaly, ataxia, and seizures syndrome: expansion of the clinical spectrum.

Neurodevelopmental disorder with microcephaly, ataxia, and seizures (NEDMAS) syndrome is a rare neurodevelopmental disorder characterized by moderate intellectual disability (ID), thin body habitus, microcephaly, seizures, ataxia, muscle weakness, and speech impairment. So far, only two families with NEDMAS have been reported. We report the clinical and molecular characteristics of three unrelated Turkish families with four NEDMAS patients. Whole-exome sequencing was used to search for the disease-causing variant. The main manifestations of the probands are severe developmental delay and ID, thin body habitus, and severe hypotonia. Brain imaging revealed bilateral cerebral and cerebellar diffuse atrophy. Sequencing results showed that both patients carried a novel missense variant c.1196C>T (p.Thr399Met) in the seryl-tRNA synthetase gene. Our findings help expand the variant spectrum of NEDMAS and provide additional information for diagnosing cases with atypical features.

Developmental genomics of limb malformations: Allelic series in association with gene dosage effects contribute to the clinical variability.

Genetic heterogeneity, reduced penetrance, and variable expressivity, the latter including asymmetric body axis plane presentations, have all been described in families with congenital limb malformations (CLMs). Interfamilial and intrafamilial heterogeneity highlight the complexity of the underlying genetic pathogenesis of these developmental anomalies. Family-based genomics by exome sequencing (ES) and rare variant analyses combined with whole-genome array-based comparative genomic hybridization were implemented to investigate 18 families with limb birth defects. Eleven of 18 (61%) families revealed explanatory variants, including 7 single-nucleotide variant alleles and 3 copy number variants (CNVs), at previously reported "disease trait associated loci": BHLHA9, GLI3, HOXD cluster, HOXD13, NPR2, and WNT10B. Breakpoint junction analyses for all three CNV alleles revealed mutational signatures consistent with microhomology-mediated break-induced replication, a mechanism facilitated by Alu/Alu-mediated rearrangement. Homozygous duplication of BHLHA9 was observed in one Turkish kindred and represents a novel contributory genetic mechanism to Gollop-Wolfgang Complex (MIM: 228250), where triplication of the locus has been reported in one family from Japan (i.e., 4n = 2n + 2n versus 4n = 3n + 1n allelic configurations). Genes acting on limb patterning are sensitive to a gene dosage effect and are often associated with an allelic series. We extend an allele-specific gene dosage model to potentially assist, in an adjuvant way, interpretations of interconnections among an allelic series, clinical severity, and reduced penetrance of the BHLHA9-related CLM spectrum.

High prevalence of multilocus pathogenic variation in neurodevelopmental disorders in the Turkish population.

Neurodevelopmental disorders (NDDs) are clinically and genetically heterogenous; many such disorders are secondary to perturbation in brain development and/or function. The prevalence of NDDs is > 3%, resulting in significant sociocultural and economic challenges to society. With recent advances in family-based genomics, rare-variant analyses, and further exploration of the Clan Genomics hypothesis, there has been a logarithmic explosion in neurogenetic "disease-associated genes" molecular etiology and biology of NDDs; however, the majority of NDDs remain molecularly undiagnosed. We applied genome-wide screening technologies, including exome sequencing (ES) and whole-genome sequencing (WGS), to identify the molecular etiology of 234 newly enrolled subjects and 20 previously unsolved Turkish NDD families. In 176 of the 234 studied families (75.2%), a plausible and genetically parsimonious molecular etiology was identified. Out of 176 solved families, deleterious variants were identified in 218 distinct genes, further documenting the enormous genetic heterogeneity and diverse perturbations in human biology underlying NDDs. We propose 86 candidate disease-trait-associated genes for an NDD phenotype. Importantly, on the basis of objective and internally established variant prioritization criteria, we identified 51 families (51/176 = 28.9%) with multilocus pathogenic variation (MPV), mostly driven by runs of homozygosity (ROHs) - reflecting genomic segments/haplotypes that are identical-by-descent. Furthermore, with the use of additional bioinformatic tools and expansion of ES to additional family members, we established a molecular diagnosis in 5 out of 20 families (25%) who remained undiagnosed in our previously studied NDD cohort emanating from Turkey.

Restless legs syndrome and headache cause sleepiness and consequent poor school performance: a community based study from Turkey.

BACKGROUND: Disturbance of sleep habits leads to excessive daytime sleepiness (EDS), which may affect learning abilities and consequently academic performance. Therefore the main purpose of current paper was to determine the prevalence of headache and Restless legs syndrome (RLS) in school-aged adolescents and to evaluate the type of headache in adolescents, with a secondary aim to determine the effect of daytime sleepiness on academic success. METHODS: This cross-sectional study was conducted on adolescents aged between 15 and 19 years of age, who were in high school education in the 2016-2017 academic years in Kahramanmaras province. A comprehensive interview form including questions on demographic data, RLS diagnostic criteria, headache and Epworth Sleepiness Scale (ESS) was applied to a total of 4151 students. RESULTS: RLS was found in 3.2% of the participants in all age groups. The mean ESS scores in adolescents with RLS were significantly higher than in those without RLS. Headache was reported by 46.9% of the adolescents in the study, with a frequency of TTH type headache of 17.7% and migraine frequency of 5.2%. RLS frequency was determined to be significantly higher in adolescents with headache and migraine. The academic success rate was significantly lower in those with higher ESS scores. CONCLUSIONS: Migraine and RLS often coexist as comorbid conditions. EDS is an important factor affecting academic success in children. Headache and RLS should not be forgotten, among other reasons for increased daytime sleepiness and its etiology.

Childhood Pineal Glioblastoma: Case Report.

Pineal glioblastomas (GBMs) are extremely rare tumors. Herein we will present a pediatric patient with GBM located in pineal region who was admitted with the symptoms of increased intracranial pressure and treated with surgical resection and radiotherapy. Introduction: Pineal region tumors are extremely rare accounting for less than 1% of all brain tumors. The most common type of pineal region tumors is germ cell tumor, followed by pineal parenchymal tumors, gliomas, atypical tumors, and the others. Case Report: A 5-year-old girl was admitted with complaints of headache, dizziness, imbalance in walking, and impaired vision for 1 month. Her neurological examination revealed a tendency to sleep, anisocoric pupillae, mesh eye pupil, dilated lateral gaze paralysis, and left hemiparasia (4/5 muscle strength). In magnetic resonance imaging, a mass was observed in the pineal region that infiltrates the right thalamus and right superior peduncle, isointense and hyperintense in T1 sections, hyperintense in T2 sections, having centrally contrasted areas in post-contrast sections. Due to the presence of evident hydrocephalus, a ventricular shunt was inserted and then through supracerebellar to infratentorial approach the lesion was removed subtotally. The histopathological diagnosis was GBM. GBMs in the pineal region are extremely rare tumors carrying poor prognosis. The patients are generally presented with the signs and symptoms of increased intracranial pressure. GBMs should be kept in mind in differential diagnosis of tumors in the pineal region.

Multiple Cerebral Hemorrhages during the Course of Guillain-Barre Syndrome: A Case Report.

Guillain-Barré syndrome (GBS) is an acute inflammatory polyneuropathy. In this report, we present a 3-year-old girl diagnosed with cortical and subcortical hemorrhage during the course of GBS who was treated with intravenous immunoglobulin. To the best of our knowledge, central nervous system hemorrhage during the course of GBS is an extremely rare condition. We believe that all clinicians following patients with GBS or using intravenous immunoglobulin for any indications should be aware of this rare but potentially life-threatening condition.

Biallelic GRM7 variants cause epilepsy, microcephaly, and cerebral atrophy.

OBJECTIVE: Defects in ion channels and neurotransmitter receptors are implicated in developmental and epileptic encephalopathy (DEE). Metabotropic glutamate receptor 7 (mGluR7), encoded by GRM7, is a presynaptic G-protein-coupled glutamate receptor critical for synaptic transmission. We previously proposed GRM7 as a candidate disease gene in two families with neurodevelopmental disorders (NDDs). One additional family has been published since. Here, we describe three additional families with GRM7 biallelic variants and deeply characterize the associated clinical neurological and electrophysiological phenotype and molecular data in 11 affected individuals from six unrelated families. METHODS: Exome sequencing and family-based rare variant analyses on a cohort of 220 consanguineous families with NDDs revealed three families with GRM7 biallelic variants; three additional families were identified through literature search and collaboration with a clinical molecular laboratory. RESULTS: We compared the observed clinical features and variants of 11 affected individuals from the six unrelated families. Identified novel deleterious variants included two homozygous missense variants (c.2671G>A:p.Glu891Lys and c.1973G>A:p.Arg685Gln) and one homozygous stop-gain variant (c.1975C>T:p.Arg659Ter). Developmental delay, neonatal- or infantile-onset epilepsy, and microcephaly were universal. Three individuals had hypothalamic-pituitary-axis dysfunction without pituitary structural abnormality. Neuroimaging showed cerebral atrophy and hypomyelination in a majority of cases. Two siblings demonstrated progressive loss of myelination by 2 years in both and an acquired microcephaly pattern in one. Five individuals died in early or late childhood. CONCLUSION: Detailed clinical characterization of 11 individuals from six unrelated families demonstrates that rare biallelic GRM7 pathogenic variants can cause DEEs, microcephaly, hypomyelination, and cerebral atrophy.

Mutations in ANKLE2, a ZIKA Virus Target, Disrupt an Asymmetric Cell Division Pathway in Drosophila Neuroblasts to Cause Microcephaly.

The apical Par complex, which contains atypical protein kinase C (aPKC), Bazooka (Par-3), and Par-6, is required for establishing polarity during asymmetric division of neuroblasts in Drosophila, and its activity depends on L(2)gl. We show that loss of Ankle2, a protein associated with microcephaly in humans and known to interact with Zika protein NS4A, reduces brain volume in flies and impacts the function of the Par complex. Reducing Ankle2 levels disrupts endoplasmic reticulum (ER) and nuclear envelope morphology, releasing the kinase Ballchen-VRK1 into the cytosol. These defects are associated with reduced phosphorylation of aPKC, disruption of Par-complex localization, and spindle alignment defects. Importantly, removal of one copy of ballchen or l(2)gl suppresses Ankle2 mutant phenotypes and restores viability and brain size. Human mutational studies implicate the above-mentioned genes in microcephaly and motor neuron disease. We suggest that NS4A, ANKLE2, VRK1, and LLGL1 define a pathway impinging on asymmetric determinants of neural stem cell division.

The Genomics of Arthrogryposis, a Complex Trait: Candidate Genes and Further Evidence for Oligogenic Inheritance.

Arthrogryposis is a clinical finding that is present either as a feature of a neuromuscular condition or as part of a systemic disease in over 400 Mendelian conditions. The underlying molecular etiology remains largely unknown because of genetic and phenotypic heterogeneity. We applied exome sequencing (ES) in a cohort of 89 families with the clinical sign of arthrogryposis. Additional molecular techniques including array comparative genomic hybridization (aCGH) and Droplet Digital PCR (ddPCR) were performed on individuals who were found to have pathogenic copy number variants (CNVs) and mosaicism, respectively. A molecular diagnosis was established in 65.2% (58/89) of families. Eleven out of 58 families (19.0%) showed evidence for potential involvement of pathogenic variation at more than one locus, probably driven by absence of heterozygosity (AOH) burden due to identity-by-descent (IBD). RYR3, MYOM2, ERGIC1, SPTBN4, and ABCA7 represent genes, identified in two or more families, for which mutations are probably causative for arthrogryposis. We also provide evidence for the involvement of CNVs in the etiology of arthrogryposis and for the idea that both mono-allelic and bi-allelic variants in the same gene cause either similar or distinct syndromes. We were able to identify the molecular etiology in nine out of 20 families who underwent reanalysis. In summary, our data from family-based ES further delineate the molecular etiology of arthrogryposis, yielded several candidate disease-associated genes, and provide evidence for mutational burden in a biological pathway or network. Our study also highlights the importance of reanalysis of individuals with unsolved diagnoses in conjunction with sequencing extended family members.

Biallelic VARS variants cause developmental encephalopathy with microcephaly that is recapitulated in vars knockout zebrafish.

Aminoacyl tRNA synthetases (ARSs) link specific amino acids with their cognate transfer RNAs in a critical early step of protein translation. Mutations in ARSs have emerged as a cause of recessive, often complex neurological disease traits. Here we report an allelic series consisting of seven novel and two previously reported biallelic variants in valyl-tRNA synthetase (VARS) in ten patients with a developmental encephalopathy with microcephaly, often associated with early-onset epilepsy. In silico, in vitro, and yeast complementation assays demonstrate that the underlying pathomechanism of these mutations is most likely a loss of protein function. Zebrafish modeling accurately recapitulated some of the key neurological disease traits. These results provide both genetic and biological insights into neurodevelopmental disease and pave the way for further in-depth research on ARS related recessive disorders and precision therapies.

Acute Mercury Poisoning in a Group of School Children.

OBJECTIVE: Elemental mercury is a toxic liquid element that is used widely in the home, medicine, agriculture, and industry. It is readily vaporized and inhaled at room temperature. Thereby, inhalation can cause acute or chronic poisoning. Mercury can be found in environmental naturally find but some dangers sources give rise to contaminations. It can be very dangerous to all living organisms, especially children. METHODS: This study presents the features of mercury poisoning in a group of pediatric cases. Data were obtained for 29 pediatric cases exposed to elemental mercury in a high school chemistry laboratory in Turkey. Patients with a blood mercury level exceeding 10 µg/L or a urine mercury level exceeding 15 µg/L were considered to have mercury poisoning. The patients were treated with 2,3-dimercaptopropane sulfonic acid or D-penicillamine. RESULTS: Twenty-nine children with mercury poisoning were admitted to the hospital. The median duration of exposure was 58 (range, 15-120) minutes. Ten (29%) children were asymptomatic. Physical and neurological examinations were normal in 19 (65.5%) children. The most common presenting complaint was headache. The most common neurological abnormality, partly dilated/dilated pupils, was present in 9 (31%) children. Mercury levels were measured in blood samples every 5 days, and the median blood mercury level was 51.98 (range, 24.9-86.4) µg/L. There was a positive correlation between the duration of exposure and maximum blood/urine mercury levels (P = 0.001). CONCLUSIONS: Elemental mercury exposure is potentially toxic; its symptomatology varies, especially in children. Secure storage of mercury and other toxic substances and provision of information about this subject to individuals who might be exposed to mercury and their families might help to prevent mercury poisoning.