Human CLP1 mutations alter tRNA biogenesis, affecting both peripheral and central nervous system function.

CLP1 is a RNA kinase involved in tRNA splicing. Recently, CLP1 kinase-dead mice were shown to display a neuromuscular disorder with loss of motor neurons and muscle paralysis. Human genome analyses now identified a CLP1 homozygous missense mutation (p.R140H) in five unrelated families, leading to a loss of CLP1 interaction with the tRNA splicing endonuclease (TSEN) complex, largely reduced pre-tRNA cleavage activity, and accumulation of linear tRNA introns. The affected individuals develop severe motor-sensory defects, cortical dysgenesis, and microcephaly. Mice carrying kinase-dead CLP1 also displayed microcephaly and reduced cortical brain volume due to the enhanced cell death of neuronal progenitors that is associated with reduced numbers of cortical neurons. Our data elucidate a neurological syndrome defined by CLP1 mutations that impair tRNA splicing. Reduction of a founder mutation to homozygosity illustrates the importance of rare variations in disease and supports the clan genomics hypothesis.

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.

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.

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.

Bi-allelic CCDC47 Variants Cause a Disorder Characterized by Woolly Hair, Liver Dysfunction, Dysmorphic Features, and Global Developmental Delay.

Ca2+ signaling is vital for various cellular processes including synaptic vesicle exocytosis, muscle contraction, regulation of secretion, gene transcription, and cellular proliferation. The endoplasmic reticulum (ER) is the largest intracellular Ca2+ store, and dysregulation of ER Ca2+ signaling and homeostasis contributes to the pathogenesis of various complex disorders and Mendelian disease traits. We describe four unrelated individuals with a complex multisystem disorder characterized by woolly hair, liver dysfunction, pruritus, dysmorphic features, hypotonia, and global developmental delay. Through whole-exome sequencing and family-based genomics, we identified bi-allelic variants in CCDC47 that encodes the Ca2+-binding ER transmembrane protein CCDC47. CCDC47, also known as calumin, has been shown to bind Ca2+ with low affinity and high capacity. In mice, loss of Ccdc47 leads to embryonic lethality, suggesting that Ccdc47 is essential for early development. Characterization of cells from individuals with predicted likely damaging alleles showed decreased CCDC47 mRNA expression and protein levels. In vitro cellular experiments showed decreased total ER Ca2+ storage, impaired Ca2+ signaling mediated by the IP3R Ca2+ release channel, and reduced ER Ca2+ refilling via store-operated Ca2+ entry. These results, together with the previously described role of CCDC47 in Ca2+ signaling and development, suggest that bi-allelic loss-of-function variants in CCDC47 underlie the pathogenesis of this multisystem disorder.

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.

Phenotypic expansion illuminates multilocus pathogenic variation.

PURPOSE: Multilocus variation-pathogenic variants in two or more disease genes-can potentially explain the underlying genetic basis for apparent phenotypic expansion in cases for which the observed clinical features extend beyond those reported in association with a "known" disease gene. METHODS: Analyses focused on 106 patients, 19 for whom apparent phenotypic expansion was previously attributed to variation at known disease genes. We performed a retrospective computational reanalysis of whole-exome sequencing data using stringent Variant Call File filtering criteria to determine whether molecular diagnoses involving additional disease loci might explain the observed expanded phenotypes. RESULTS: Multilocus variation was identified in 31.6% (6/19) of families with phenotypic expansion and 2.3% (2/87) without phenotypic expansion. Intrafamilial clinical variability within two families was explained by multilocus variation identified in the more severely affected sibling. CONCLUSION: Our findings underscore the role of multiple rare variants at different loci in the etiology of genetically and clinically heterogeneous cohorts. Intrafamilial phenotypic and genotypic variability allowed a dissection of genotype-phenotype relationships in two families. Our data emphasize the critical role of the clinician in diagnostic genomic analyses and demonstrate that apparent phenotypic expansion may represent blended phenotypes resulting from pathogenic variation at more than one locus.

Neuroinfluenza: evaluation of seasonal influenza associated severe neurological complications in children (a multicenter study).

PURPOSE: Although influenza primarily affects the respiratory system, in some cases, it can cause severe neurological complications. Younger children are especially at risk. Pediatric literature is limited on the diagnosis, treatment, and prognosis of influenza-related neurological complications. The aim of the study was to evaluate children who suffered severe neurological manifestation as a result of seasonal influenza infection. METHODS: The medical records of 14 patients from six hospitals in different regions of the country were evaluated. All of the children had a severe neurological manifestations related to laboratory-confirmed influenza infection. RESULTS: Median age of the patients was 59 months (6 months-15.5 years) and nine (64.3%) were male. Only 4 (28.6%) of the 14 patients had a comorbid disease. Two patients were admitted to hospital with influenza-related late complications, and the remainder had acute complication. The most frequent complaints at admission were fever, altered mental status, vomiting, and seizure, respectively. Cerebrospinal fluid (CSF) analysis was performed in 11 cases, and pleocytosis was found in only two cases. Neuroradiological imaging was performed in 13 patients. The most frequent affected regions of nervous system were as follows: cerebellum, brainstem, thalamus, basal ganglions, periventricular white matter, and spinal cords. Nine (64.3%) patients suffered epileptic seizures. Two patients had focal seizure, and the rest had generalized seizures. Two patients developed status epilepticus. Most frequent diagnoses of patients were encephalopathy (n = 4), encephalitis (n = 3), and meningitis (n = 3), respectively. The rate of recovery without sequelae from was found to be 50%. At discharge, three (21.4%) patients had mild symptoms, another three (21.4%) had severe neurological sequelae. One (7.1%) patient died. The clinical findings were more severe and outcome was worse in patients <5 years old than patients >5 years old and in patients with comorbid disease than previously healthy group. CONCLUSION: Seasonal influenza infection may cause severe neurological complications, especially in children. Healthy children are also at risk such as patients with comorbid conditions. All children who are admitted with neurological findings, especially during the influenza season, should be evaluated for influenza-related neurological complications even if their respiratory complaints are mild or nonexistent.

Idiopathic Unilateral Paralysis of the Palate in a Youth.

Unilateral isolated paralysis of the soft palate is a rare clinical entity that is associated with rhinolalia and the flow of nasal fluids from the nostril on the affected side. We report a case of a 17-year-old boy admitted complaining of nasal speech and drinks flowing into his right nostril. Most cases of soft palate palsy are idiopathic, whereas a few cases are caused by viral infections or tumors. We describe an isolated case of soft palate palsy with spontaneous recovery within 1 month.

Ecthyma gangrenosum in an infant after liver transplantation.

Ecthyma gangrenosum is a rare, necrotizing, bacterial infection of the skin most commonly caused by Pseudomonas aeruginosa. It has a characteristic clinical picture starting with maculopapular eruption followed by hemorrhagic vesicle and evolving into gangrenous ulcer. Although direct skin inoculation without septicemia is also probable, usually ecthyma gangrenosum is pathognomonic for Pseudomonas septicemia, which has a mortality rate of 38-96%. Herein, we report on the case of a 9-month-old male infant diagnosed with ecthyma gangrenosum who had undergone liver transplantation approximately 6 months previously and who was under immunosuppressive treatment, in order to highlight the importance of the early diagnosis and treatment of this disease.

Frequency of coeliac disease in children with breath-holding spells.

AIM: Iron deficiency anaemia (IDA), which is reported very commonly among patients with breath holding spells (BHS), is the most common presentation of coeliac disease (CD). In that aspect, IDA may be a common pathway linking these two diseases. The aim of this study was to evaluate the frequency of CD in patients with BHS. METHODS: We studied 348 children with BHS, and 470 age- and sex-matched controls with no known disease. Serological screening for CD was performed in all patients by searching for serum tissue transglutaminase immunoglobulin A. RESULTS: The first group consisted of 348 children with BHS (231 males, 117 females; mean age 2.23 ± 1.84 years), and the second group consisted of 470 healthy children (284 males, 186 females; mean age 2.11 ± 1.98 years). A total of 300 (86.2%) patients had cyanotic type of BHS only, 27 (7.8%) had pallid type of BHS only and 21 (6%) had mixed type of BHS. The prevalence of IDA was statistically significantly higher in BHS patients compared with controls. Tissue transglutaminase immunoglobulin A was not detected as positive in any patients in either group; therefore, endoscopic and histopathological examinations were not performed. CONCLUSIONS: Our report is the first to describe the frequency of tissue transglutaminase immunoglobulin A positivity in patients with BHS. There was no evidence of a relationship between CD and BHS, but IDA seems to be an important risk factor in the development of BHS. Therefore, serological screening for CD in patients with BHS does not seem to be necessary.

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.

Neurobrucellosis developing unilateral oculomotor nerve paralysis.

Brucellosis is a zoonotic infectious disease that is common around the world. Its clinical course demonstrates great diversity as it can affect all organs and systems. However, the central nervous system is rarely affected in the pediatric population. Neurobrucellosis is most frequently observed with meningitis and has numerous complications, including meningocephalitis, myelitis, cranial nerve paralyses, radiculopathy, and neuropathy. Neurobrucellosis affects the second, third, sixth, seventh, and eighth cranial nerves. Involvement of the oculomotor nerves is a very rare complication in neurobrucellosis although several adult cases have been reported. In this article, we present the case of a 9-year-old girl who developed unilateral nerve paralysis as a secondary complication of neurobrucellosis and recovered without sequel after treatment. This case is notable because it is a very rare, the first within the pediatric population. Our article emphasizes that neurobrucellosis should be considered among the distinguishing diagnoses in every case that is admitted for nerve paralysis in regions where Brucella infection is endemic.

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.