Phenotypic and functional assessment of two novel KCNQ2 gain-of-function variants Y141N and G239S and effects of amitriptyline treatment.

While loss-of-function (LoF) variants in KCNQ2 are associated with a spectrum of neonatal-onset epilepsies, gain-of-function (GoF) variants cause a more complex phenotype that precludes neonatal-onset epilepsy. In the present work, the clinical features of three patients carrying a de novo KCNQ2 Y141N (n â€‹= â€‹1) or G239S variant (n â€‹= â€‹2) respectively, are described. All three patients had a mild global developmental delay, with prominent language deficits, and strong activation of interictal epileptic activity during sleep. Epileptic seizures were not reported. The absence of neonatal seizures suggested a GoF effect and prompted functional testing of the variants. In vitro whole-cell patch-clamp electrophysiological experiments in Chinese Hamster Ovary cells transiently-transfected with the cDNAs encoding Kv7.2 subunits carrying the Y141N or G239S variants in homomeric or heteromeric configurations with Kv7.2 subunits, revealed that currents from channels incorporating mutant subunits displayed increased current densities and hyperpolarizing shifts of about 10 â€‹mV in activation gating; both these functional features are consistent with an in vitro GoF phenotype. The antidepressant drug amitriptyline induced a reversible and concentration-dependent inhibition of current carried by Kv7.2 Y141N and G239S mutant channels. Based on in vitro results, amitriptyline was prescribed in one patient (G239S), prompting a significant improvement in motor, verbal, social, sensory and adaptive behavior skillsduring the two-year-treatment period. Thus, our results suggest that KCNQ2 GoF variants Y141N and G239S cause a mild DD with prominent language deficits in the absence of neonatal seizures and that treatment with the Kv7 channel blocker amitriptyline might represent a potential targeted treatment for patients with KCNQ2 GoF variants.

The novel P330L pathogenic variant of aromatic amino acid decarboxylase maps on the catalytic flexible loop underlying its crucial role.

Aromatic amino acid decarboxylase (AADC) deficiency is a rare monogenic disease, often fatal in the first decade, causing severe intellectual disability, movement disorders and autonomic dysfunction. It is due to mutations in the gene coding for the AADC enzyme responsible for the synthesis of dopamine and serotonin. Using whole exome sequencing, we have identified a novel homozygous c.989C > T (p.Pro330Leu) variant of AADC causing AADC deficiency. Pro330 is part of an essential structural and functional element: the flexible catalytic loop suggested to cover the active site as a lid and properly position the catalytic residues. Our investigations provide evidence that Pro330 concurs in the achievement of an optimal catalytic competence. Through a combination of bioinformatic approaches, dynamic light scattering measurements, limited proteolysis experiments, spectroscopic and in solution analyses, we demonstrate that the substitution of Pro330 with Leu, although not determining gross conformational changes, results in an enzymatic species that is highly affected in catalysis with a decarboxylase catalytic efficiency decreased by 674- and 194-fold for the two aromatic substrates. This defect does not lead to active site structural disassembling, nor to the inability to bind the pyridoxal 5'-phosphate (PLP) cofactor. The molecular basis for the pathogenic effect of this variant is rather due to a mispositioning of the catalytically competent external aldimine intermediate, as corroborated by spectroscopic analyses and pH dependence of the kinetic parameters. Altogether, we determined the structural basis for the severity of the manifestation of AADC deficiency in this patient and discussed the rationale for a precision therapy.

FINCA syndrome-Defining neurobehavioral phenotype in survivors into late childhood.

We report for the first time a novel missense variant in NHLRC2. We extend the NHLRC2 gene associated neuropsychological and neuroimaging phenotype, and propose that the NHLRC2 gene should be considered in patients with symptoms of atypical Rett syndrome. We also summarise currently available literature on neuropsychological symptoms in children with FINCA who survived into late childhood.

The case of fatal acute hemorrhagic necrotizing encephalitis in a two-month-old boy with Covid-19.

SARS-CoV-2 infection in healthy children is usually benign. However, severe, life-threatening cases have previously been reported, notably in infants. We must be aware that data on the natural history of COVID-19 are still full of gaps, especially as far as the pediatric population is concerned. Therefore, it is important to describe rare manifestations of SARS-CoV-2 acute infection in children. Here we present the case of acute hemorrhagic necrotizing encephalitis (AHNE) in a previously healthy, 2-month-old male infant with SARS-CoV-2 infection. After 2 days of fever with signs of respiratory tract infection, neurological manifestations appeared: irritability, nystagmus, agitation then apathy. As a consequence of apnea, he required emergent intubation and was transferred to our PICU. Brain MRI revealed diffuse areas of oedema associated with numerous symmetrical changes with punctate hemorrhages in basal ganglia, thalami, brainstem, and cerebral gray matter. CSF was clear with pleocytosis 484 cells/µl, elevated lactic acid and protein. Despite broad microbiological testing, only SARS-CoV2 was detected in PCR nasal swab. Therefore, acute hemorrhagic necrotizing encephalitis (AHNE) as a result of COVID-19 was the most probable diagnosis. The outcome was unfavorable - brain death was confirmed, life support was withdrawn.

Spinal muscular atrophy: epidemiology and health burden in children - a Polish national healthcare database perspective before introduction of SMA-specific treatment.

INTRODUCTION: Spinal muscular atrophy (SMA) is one of the most frequent autosomal recessive neuromuscular disorders. It leads to progressive muscle weakness, premature death or permanent ventilation. Significant disability, scoliosis, severe pulmonary infections and other problems require in- and outpatient medical care. Various approaches have been used to evaluate SMA epidemiology, healthcare burden and adherence to standard of care. The recent introduction of pharmacological treatment in a large SMA population will change the course of the disease and the healthcare requirements of patients. MATERIAL AND METHODS: We have used the National Health Fund database to identify children with SMA and the healthcare service they received in the pre-pharmacological treatment era. Pivotal phase II and III medical trials for nusinersen were conducted between 2013 and 2015. The National Treatment Programme of SMA patients with nusinersen in our country was started in January 2019. The year 2014 was used to evaluate incident cases. RESULTS: 51 new SMA cases (incidence 1:7,356) and 518 SMA patients younger than 18 were identified in 2014. 32 (6.2%) deaths were recorded, half in the first two years of life. 35 (6.8%) patients received palliative and 115 (22.2%) long-term care (including assisted ventilation). A total number of 3,057 days of hospital stay were reported. Only 65/518 (12.6%) patients did not receive publicly-funded healthcare service other than specialist or general practitioner's consultation. CONCLUSIONS: SMA caused significant mortality and morbidity in children. The National Health Fund database can be used to reliably record incident cases and track the care provided to paediatric SMA patients.

Variants of ATP1A3 in residue 756 cause a separate phenotype of relapsing encephalopathy with cerebellar ataxia (RECA)-Report of two cases and literature review.

BACKGROUND: Variants in ATP1A3 cause well-known phenotypes-alternating hemiplegia of childhood (AHC), rapid-onset dystonia-parkinsonism (RDP), cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss (CAPOS), and severe early infantile epileptic encephalopathy. Recently, there has been growing evidence for genotype-phenotype correlations in the ATP1A3 variants, and a separate phenotype associated with variants in residue 756-two acronyms are proposed for the moment-FIPWE (fever-induced paroxysmal weakness and encephalopathy) and RECA (relapsing encephalopathy with cerebellar ataxia). MATERIALS AND METHODS: Herein, we are describing two new pediatric cases with a p.Arg756His change in the ATP1A3 gene. Both patients have had more than one episode of a neurological decompensation triggered by fever with severe hypotonia and followed by ataxia. Thirty-three cases from literature were analyzed to define and strengthen the genotype-phenotype correlation of variants located in residue 756 (p.Arg756His, p.Arg756Cys, p.Arg756Leu). CONCLUSIONS: Patients with a ATP1A3 variant in residue 756 are characterized by recurrent paroxysmal episodes of neurological decompensations triggered by fever, with severe hypotonia, ataxia, dysarthria, symptoms from the orofacial area (dysphagia, drooling) as well as with altered consciousness. Recovery is slow and usually not full with the persistent symptoms of cerebellar ataxia, dysarthria, dystonic and choreiform movements.

Kabuki Syndrome-Clinical Review with Molecular Aspects.

Kabuki syndrome (KS) is a rare developmental disorder principally comprised of developmental delay, hypotonia and a clearly defined dysmorphism: elongation of the structures surrounding the eyes, a shortened and depressed nose, thinning of the upper lip and thickening of the lower lip, large and prominent ears, hypertrichosis and scoliosis. Other characteristics include poor physical growth, cardiac, gastrointestinal and renal anomalies as well as variable behavioral issues, including autistic features. De novo or inherited pathogenic/likely pathogenic variants in the KMT2D gene are the most common cause of KS and account for up to 75% of patients. Variants in KDM6A cause up to 5% of cases (X-linked dominant inheritance), while the etiology of about 20% of cases remains unknown. Current KS diagnostic criteria include hypotonia during infancy, developmental delay and/or intellectual disability, typical dysmorphism and confirmed pathogenic/likely pathogenic variant in KMT2D or KDM6A. Care for KS patients includes the control of physical and psychomotor development during childhood, rehabilitation and multi-specialist care. This paper reviews the current clinical knowledge, provides molecular and scientific links and sheds light on the treatment of Kabuki syndrome individuals.

Elevated Dipeptidyl Peptidase IV (DPP-IV) Activity in Plasma from Patients with Various Lysosomal Diseases.

Increased activity of dipeptidyl peptidase IV (DPP-IV) was reported earlier in patients with different types of mucopolysaccharidoses. DPP-IV (also known as CD26 lymphocyte T surface antigen) is a transmembrane protein showing protease activity. This enzyme displays various functions in the organism and plays an important role in multiple processes like glucose metabolism, nociception, cell-adhesion, psychoneuroendocrine regulation, immune response and cardiovascular adaptation. In order to evaluate DPP-IV in lysosomal storage diseases (LSD), we examined its activity in plasma samples from 307 patients affected with 24 different LSDs and in 75 control persons. Our results revealed elevated DPP-IV activity especially in individuals affected with mucolipidosis II/III, alpha-mannosidosis, and mucopolysaccharidoses types III, II, and I (p < 0.05). In other LSDs the DPP-IV activity was still significantly increased, but to a lesser extent. In patients with Gaucher disease, ceroid lipofuscinosis type 1 (CLN1), Niemann-Pick disease type C and A, Krabbe and Pompe diseases, gangliosidosis GM2 and metachromatic leukodystrophy discreet or no changes in DPP-IV activity were observed. DPP-IV may serve as a first-tier diagnostic procedure or additional biochemical analysis in recognizing patients with some LSDs. DPP-IV may become an object of basic research for a better understanding of LSDs.

De novo stop-loss variants in CLDN11 cause hypomyelinating leukodystrophy.

Claudin-11, a tight junction protein, is indispensable in the formation of the radial component of myelin. Here, we report de novo stop-loss variants in the gene encoding claudin-11, CLDN11, in three unrelated individuals presenting with an early-onset spastic movement disorder, expressive speech disorder and eye abnormalities including hypermetropia. Brain MRI showed a myelin deficit with a discrepancy between T1-weighted and T2-weighted images and some progress in myelination especially involving the central and peripheral white matter. Exome sequencing identified heterozygous stop-loss variants c.622T>C, p.(*208Glnext*39) in two individuals and c.622T>G, p.(*208Gluext*39) in one individual, all occurring de novo. At the RNA level, the variant c.622T>C did not lead to a loss of expression in fibroblasts, indicating this transcript is not subject to nonsense-mediated decay and most likely translated into an extended protein. Extended claudin-11 is predicted to form an alpha helix not incorporated into the cytoplasmic membrane, possibly perturbing its interaction with intracellular proteins. Our observations suggest that stop-loss variants in CLDN11 expand the genetically heterogeneous spectrum of hypomyelinating leukodystrophies.

POLG gene mutation. Clinico-neuropathological study.

We present a female patient with a mutation of the POLG gene (POLG DNA polymerase gamma, catalytic subunit; *174763) in which the clinical course suggested a mitochondrial disease, a neuropathological examination identified the syndrome more closely, and a genetic test confirmed the disease. Apart from the morphological lesions typical of Alpers-Huttenlocher syndrome, rarely observed symmetrical degenerative changes in the accessory olivary nuclei were found. It was unusual in the clinical course of the disease that pancreatitis was diagnosed before symptoms of liver failure appeared.

[Cerebral salt wasting syndrome as a complication of subarachnoid hemorrhage in a girl with nephrotic syndrome - a case report]. / Mózgowy zespól utraty soli jako powiklanie krwawienia podpajeczynówkowego u dziewczynki z zespolem nerczycowym ­ opis przypadku.

INTRODUCTION: Cerebral salt wasting syndrome (CSWS), characterized by natriuresis, polyuria, and hypovolemia, is a rare complication of central nervous system injury or disease. A CASE STUDY: 12-year-old girl was admitted with second attack of nephrotic syndrome (NS). On admission she presents with edema, blood pressure 110/60 mm Hg, proteinuria 145 mg/kg/24h, hypoalbuminemia (1.7 g/dL), GFR 94.4 mL/min/1.73m2, sodium 133 mmol/L. On 5th day the patient developed thrombosis of right subclavian and axillary vein and was treated with recombinant tissue plasminogen activator (0.3 mg/kg/h i.v.). 45 minutes after onset of the infusion severe headache appeared. Computed tomography revealed subarachnoid hemorrhage in a region of left occipital lobe and posterior 1/3 part of sickle of the brain. Control ultrasonography examination revealed resolution of the thrombus. No deficits were found on neurologic examination. Proteinuria subsided on 11th day of hospitalization. After the hemorrhage hypovolemia, hypotension (80/40 - 100/60 mm Hg, heart rate 100/min), polyuria, and pathologic natriuresis (up to 13.0 mmol/kg/24h) were observed. Cerebral salt wasting syndrome was recognized. The girl was supplemented with oral and intravenous sodium (up to 10 mmol/ kg/24h). In following days gradual decrease of diuresis and urinary sodium loss was observed. The patient was discharged home after 41 days with normal diuresis (1.5l/24h) and natriuresis (1.44 mmol/kg/24h). CONCLUSIONS: Treatment of thromboembolic complications in children with NS poses a risk of central nervous system bleeding. Serum sodium concentration and diuresis must be strictly monitored in patients with central nervous system lesion, especially in the course of nephrotic syndrome.

Novel calcineurin A (PPP3CA) variant associated with epilepsy, constitutive enzyme activation and downregulation of protein expression.

PPP3CA encodes calmodulin-binding catalytic subunit of calcineurin, a ubiquitously expressed calcium/calmodulin-regulated protein phosphatase. Recently de novo PPP3CA variants were reported as a cause of disease in 12 subjects presenting with epileptic encephalopathy and dysmorphic features. We describe a boy with similar phenotype and severe early onset epileptic encephalopathy in whom a novel de novo c.1324C>T (p.(Gln442Ter)) PPP3CA variant was found by whole exome sequencing. Western blot experiments in patient's cells (EBV transformed lymphocytes and neuronal cells derived through reprogramming) indicate that despite normal mRNA abundance the protein expression level is strongly reduced both for the mutated and wild-type protein. By in vitro studies with recombinant protein expressed in E. coli we show that c.1324C>T (p.(Gln442Ter)) results in constitutive activation of the enzyme. Our results confirm the role of PPP3CA defects in pathogenesis of a distinct neurodevelopmental disorder including severe epilepsy and dysmorphism and provide further functional clues regarding the pathogenic mechanism.

Neurodevelopmental phenotype caused by a de novo PTPN4 single nucleotide variant disrupting protein localization in neuronal dendritic spines.

Protein tyrosine phosphatase non-receptor type 4 (PTPN4) encodes non-receptor protein tyrosine phosphatase implicated in synaptic plasticity and innate immune response. The only report of PTPN4-associated disease described a neurodevelopmental disorder associated with a whole gene deletion. We describe a child with developmental delay, autistic features, hypotonia, increased immunoglobulin E and dental problems with a novel mosaic de novo variant in PTPN4 (hg19 chr2:g.120620188 T > C, NM_002830.3:p.[Leu72Ser]/c.215T>C) located in domain that controls protein subcellular distribution. Studies in mouse hippocampal neurons transfected with non-mutated or mutated human PTPN4 showed that despite their similar expression in neurons the mutated protein was absent from dendritic spines. Next, we studied patient's primary blood mononuclear cells' response to lipopolysaccharide stimulation and found no difference from control in phosphorylation of TBK1 and IRF3 (involved in Toll-like receptor 4 signaling) and induction of cytokines' messenger RNA. We conclude that the PTPN4 p.(Leu72Ser) variant is a likely cause of neurodevelopmental symptoms of our proband whereas its role in immune dysfunction requires further studies.

Novel GNB1 de novo mutation in a patient with neurodevelopmental disorder and cutaneous mastocytosis: Clinical report and literature review.

De novo monoallelic mutations in the GNB1 gene, encoding a ß subunit of heterotrimeric G proteins, cause a newly recognized disorder with the typical clinical picture of severe developmental delay/intellectual disability, hypotonia and extrapyramidal symptoms. We describe another case of the condition with manifestations of cutaneous mastocytosis associated with a novel do novo mutation GNB1NM_001282539.1: c.230G > T; p.(Gly77Val). We also present the detailed clinical and etiopathogenetic discussion on previously diagnosed patients as well as suggestions for the link of the mutation with skin disease.

Proteomics in the Diagnosis of Inborn Encephalopathies of Unknown Origin: A Myth or Reality.

Synaptopathy underlies a great variety of neurological or neurodevelopmental disorders, including neurodegenerative diseases and the highly complex neuropsychiatric syndromes. Standard diagnostic assays in the majority of synaptopathies are insufficient to make an appropriate and fast diagnosis, which has spurred a search for more accurate diagnostic methods using recent technological advances. As synaptopathy phenotypes strictly depend on genetics and environmental factors, the best way to approach these diseases is the investigation of entire sets of protein characteristics. Thus, proteomics has emerged as a mainstay in the studies on synaptopathies, with mass spectrometry as a technology of choice. This review is an update on the proteomic methods and achievements in the understanding, diagnostics, and novel biomarkers of synaptopathies. The article also provides a critical point of view and future perspectives on the application of neuroproteomics in clinical practice.

Clinico-pathological correlation in case of BRAT1 mutation.

The clinical picture of BRCA1-associated protein required for ATM activation-1 (BRAT1) comprises retractable early-onset epileptic encephalopathy, progressive microcephaly, and early demise. Both, inter- and intrafamilial variations of features of BRAT1-associated disease have been described. Here, the familial case of a brother and sister with homozygous pathogenic variants in BRAT1 is presented with special emphasis on differences in seizure type/onset and central nervous system lesions. The neuropathology is extensively discussed and hypotheses put forward that may shed light on etiology of brain symptomatology within the context of BRAT1 mutations.

Isolated Hearing Impairment Caused by SPATA5 Mutations in a Family with Variable Phenotypic Expression.

Biallelic mutations in the SPATA5 gene, encoding ATPase family protein, are an important cause of newly recognized epileptic encephalopathy classified as epilepsy, hearing loss, and mental retardation syndrome (EHLMRS, OMIM: 616577). Herein we describe a family in which two SPATA5 mutations with established pathogenicity (p.Thr330del and c.1714+1G>A) were found in the proband and her younger sister. The proband had a similar clinical picture to the previous descriptions of EHLMRS. In the sister, the only manifestation was an isolated sensorineural hearing loss. Our findings extend the phenotypic spectrum of SPATA5-associated diseases and indicate that SPATA5 defects may account for a fraction of isolated sensorineural hearing impairment cases.