CUX1-related neurodevelopmental disorder: deep insights into phenotype-genotype spectrum and underlying pathology.

Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1+/- mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals). We analyze brain CUX1 expression and susceptibility to epilepsy in Cux1+/- mice. We describe 34 individuals, from which 30 were unrelated, with 26 different null and four missense variants. The leading symptoms were mild to moderate delayed speech and motor development and borderline to moderate intellectual disability. Additional symptoms were muscular hypotonia, seizures, joint laxity, and abnormalities of the forehead. In Cux1+/- mice, we found delayed growth, histologically normal brains, and increased susceptibility to seizures. In Cux1+/- brains, the expression of Cux1 transcripts was half of WT animals. Expression of CUX1 proteins was reduced, although in early postnatal animals significantly more than in adults. In summary, disease-causing CUX1 variants result in a non-syndromic phenotype of developmental delay and intellectual disability. In some individuals, this phenotype ameliorates with age, resulting in a clinical catch-up and normal IQ in adulthood. The post-transcriptional balance of CUX1 expression in the heterozygous brain at late developmental stages appears important for this favorable clinical course.

Erratum: Variants in PHF8 cause a spectrum of X-linked neurodevelopmental disorders and facial dysmorphology.

[This corrects the article DOI: 10.1016/j.xhgg.2022.100102.].

Variants in PHF8 cause a spectrum of X-linked neurodevelopmental disorders and facial dysmorphology.

Loss-of-function variants in PHD Finger Protein 8 (PHF8) cause Siderius X-linked intellectual disability (ID) syndrome, hereafter called PHF8-XLID. PHF8 is a histone demethylase that is important for epigenetic regulation of gene expression. PHF8-XLID is an under-characterized disorder with only five previous reports describing different PHF8 predicted loss-of-function variants in eight individuals. Features of PHF8-XLID include ID and craniofacial dysmorphology. In this report we present 16 additional individuals with PHF8-XLID from 11 different families of diverse ancestry. We also present five individuals from four different families who have ID and a variant of unknown significance in PHF8 with no other explanatory variant in another gene. All affected individuals exhibited developmental delay and all but two had borderline to severe ID. Of the two who did not have ID, one had dyscalculia and the other had mild learning difficulties. Craniofacial findings such as hypertelorism, microcephaly, elongated face, ptosis, and mild facial asymmetry were found in some affected individuals. Orofacial clefting was seen in three individuals from our cohort, suggesting that this feature is less common than previously reported. Autism spectrum disorder and attention deficit hyperactivity disorder, which were not previously emphasized in PHF8-XLID, were frequently observed in affected individuals. This series expands the clinical phenotype of this rare ID syndrome caused by loss of PHF8 function.

Variants in ADD1 cause intellectual disability, corpus callosum dysgenesis, and ventriculomegaly in humans.

PURPOSE: Adducins interconnect spectrin and actin filaments to form polygonal scaffolds beneath the cell membranes and form ring-like structures in neuronal axons. Adducins regulate mouse neural development, but their function in the human brain is unknown. METHODS: We used exome sequencing to uncover ADD1 variants associated with intellectual disability (ID) and brain malformations. We studied ADD1 splice isoforms in mouse and human neocortex development with RNA sequencing, super resolution imaging, and immunoblotting. We investigated 4 variant ADD1 proteins and heterozygous ADD1 cells for protein expression and ADD1-ADD2 dimerization. We studied Add1 functions in vivo using Add1 knockout mice. RESULTS: We uncovered loss-of-function ADD1 variants in 4 unrelated individuals affected by ID and/or structural brain defects. Three additional de novo copy number variations covering the ADD1 locus were associated with ID and brain malformations. ADD1 is highly expressed in the neocortex and the corpus callosum, whereas ADD1 splice isoforms are dynamically expressed between cortical progenitors and postmitotic neurons. Human variants impair ADD1 protein expression and/or dimerization with ADD2. Add1 knockout mice recapitulate corpus callosum dysgenesis and ventriculomegaly phenotypes. CONCLUSION: Our human and mouse genetics results indicate that pathogenic ADD1 variants cause corpus callosum dysgenesis, ventriculomegaly, and/or ID.

Rare deleterious mutations of HNRNP genes result in shared neurodevelopmental disorders.

BACKGROUND: With the increasing number of genomic sequencing studies, hundreds of genes have been implicated in neurodevelopmental disorders (NDDs). The rate of gene discovery far outpaces our understanding of genotype-phenotype correlations, with clinical characterization remaining a bottleneck for understanding NDDs. Most disease-associated Mendelian genes are members of gene families, and we hypothesize that those with related molecular function share clinical presentations. METHODS: We tested our hypothesis by considering gene families that have multiple members with an enrichment of de novo variants among NDDs, as determined by previous meta-analyses. One of these gene families is the heterogeneous nuclear ribonucleoproteins (hnRNPs), which has 33 members, five of which have been recently identified as NDD genes (HNRNPK, HNRNPU, HNRNPH1, HNRNPH2, and HNRNPR) and two of which have significant enrichment in our previous meta-analysis of probands with NDDs (HNRNPU and SYNCRIP). Utilizing protein homology, mutation analyses, gene expression analyses, and phenotypic characterization, we provide evidence for variation in 12 HNRNP genes as candidates for NDDs. Seven are potentially novel while the remaining genes in the family likely do not significantly contribute to NDD risk. RESULTS: We report 119 new NDD cases (64 de novo variants) through sequencing and international collaborations and combined with published clinical case reports. We consider 235 cases with gene-disruptive single-nucleotide variants or indels and 15 cases with small copy number variants. Three hnRNP-encoding genes reach nominal or exome-wide significance for de novo variant enrichment, while nine are candidates for pathogenic mutations. Comparison of HNRNP gene expression shows a pattern consistent with a role in cerebral cortical development with enriched expression among radial glial progenitors. Clinical assessment of probands (n = 188-221) expands the phenotypes associated with HNRNP rare variants, and phenotypes associated with variation in the HNRNP genes distinguishes them as a subgroup of NDDs. CONCLUSIONS: Overall, our novel approach of exploiting gene families in NDDs identifies new HNRNP-related disorders, expands the phenotypes of known HNRNP-related disorders, strongly implicates disruption of the hnRNPs as a whole in NDDs, and supports that NDD subtypes likely have shared molecular pathogenesis. To date, this is the first study to identify novel genetic disorders based on the presence of disorders in related genes. We also perform the first phenotypic analyses focusing on related genes. Finally, we show that radial glial expression of these genes is likely critical during neurodevelopment. This is important for diagnostics, as well as developing strategies to best study these genes for the development of therapeutics.

Tissue variations of mosaic genome-wide paternal uniparental disomy and phenotype of multi-syndromal congenital hyperinsulinism.

Mosaic genome-wide paternal uniparental disomy (GW-pUPD) is a rarely recognised disorder. The phenotypic manifestations of multilocus imprinting defects (MLIDs) remain unclear. We report of an apparently non-syndromic infant with severe congenital hyperinsulinism (CHI) and diffuse pancreatic labelling by 18F*-DOPA-PET/CT leading to near-total pancreatectomy. The histology was atypical with pronounced proliferation of endocrine cells comprising >70% of the pancreatic tissue and a small pancreatoblastoma. Routine genetic analysis for CHI was normal in the blood and resected pancreatic tissue. At two years' age, Beckwith-Wiedemann Syndrome (BWS) stigmata emerged, and at five years a liver tumour with focal nodular hyperplasia and an adrenal tumour were resected. pUPD was detected in 11p15 and next in the entire chromosome 11 with microsatellite markers. Quantitative fluorescent PCR with amplification of chromosome-specific DNA sequences for chromosomes 13, 18, 21 and X indicated GW-pUPD. A next generation sequencing panel with 303 SNPs on 21 chromosomes showed pUPD in both blood and pancreatic tissue. The mosaic distribution of GW-pUPD ranged from 31 to 35% in blood and buccal swap to 74% in the resected pancreas, 80% in a non-tumour liver biopsy, and 100% in the liver focal nodular hyperplasia and adrenal tumour. MLID features included transient conjugated hyperbilirubinaemia and lack of macrosomia from BWS (pUPD6); and behavioural and psychomotor manifestations of Angelman Syndrome (pUPD15) on follow-up. In conclusion, atypical pancreatic histology in apparently non-syndromic severe CHI patients may be the first clue to BWS and multi-syndromal CHI from GW-pUPD. Variations in the degree of mosaicism between tissues explained the phenotype.

Neurologic phenotypes associated with COL4A1/2 mutations: Expanding the spectrum of disease.

OBJECTIVE: To characterize the neurologic phenotypes associated with COL4A1/2 mutations and to seek genotype-phenotype correlation. METHODS: We analyzed clinical, EEG, and neuroimaging data of 44 new and 55 previously reported patients with COL4A1/COL4A2 mutations. RESULTS: Childhood-onset focal seizures, frequently complicated by status epilepticus and resistance to antiepileptic drugs, was the most common phenotype. EEG typically showed focal epileptiform discharges in the context of other abnormalities, including generalized sharp waves or slowing. In 46.4% of new patients with focal seizures, porencephalic cysts on brain MRI colocalized with the area of the focal epileptiform discharges. In patients with porencephalic cysts, brain MRI frequently also showed extensive white matter abnormalities, consistent with the finding of diffuse cerebral disturbance on EEG. Notably, we also identified a subgroup of patients with epilepsy as their main clinical feature, in which brain MRI showed nonspecific findings, in particular periventricular leukoencephalopathy and ventricular asymmetry. Analysis of 15 pedigrees suggested a worsening of the severity of clinical phenotype in succeeding generations, particularly when maternally inherited. Mutations associated with epilepsy were spread across COL4A1 and a clear genotype-phenotype correlation did not emerge. CONCLUSION: COL4A1/COL4A2 mutations typically cause a severe neurologic condition and a broader spectrum of milder phenotypes, in which epilepsy is the predominant feature. Early identification of patients carrying COL4A1/COL4A2 mutations may have important clinical consequences, while for research efforts, omission from large-scale epilepsy sequencing studies of individuals with abnormalities on brain MRI may generate misleading estimates of the genetic contribution to the epilepsies overall.

De Novo Variants in GRIA4 Lead to Intellectual Disability with or without Seizures and Gait Abnormalities.

Using trio whole-exome sequencing, we have identified de novo heterozygous pathogenic variants in GRIA4 in five unrelated individuals with intellectual disability and other symptoms. GRIA4 encodes an AMPA receptor subunit known as GluR4, which is found on excitatory glutamatergic synapses and is important for learning and memory. Four of the variants are located in the highly conserved SYTANLAAF motif in the transmembrane protein M3, and the fifth is in an extra-cellular domain. Molecular modeling of the altered protein showed that three of the variants in the SYTANLAAF motif orient toward the center of the pore region and most likely lead to disturbance of the gating mechanism. The fourth variant in the SYTANLAAF motif most likely results in reduced permeability. The variant in the extracellular domain potentially interferes with the binding between the monomers. On the basis of clinical information and genetic results, and the fact that other subunits of the AMPA receptor have already been associated with neurodevelopmental disorders, we suggest that pathogenic de novo variants in GRIA4 lead to intellectual disability with or without seizures, gait abnormalities, problems of social behavior, and other variable features.

Both Low Blood Glucose and Insufficient Treatment Confer Risk of Neurodevelopmental Impairment in Congenital Hyperinsulinism: A Multinational Cohort Study.

BACKGROUND/AIMS: Congenital hyperinsulinism (CHI) is a heterogeneous disease most frequently caused by KATP-channel (ABCC8 and KCNJ11) mutations, with neonatal or later onset, variable severity, and with focal or diffuse pancreatic involvement as the two major histological types. CHI confers a high risk of neurological impairment; however, sparsely studied in larger patient series. We assessed the neurodevelopmental outcome in children with CHI at follow-up in a mixed international cohort. METHODS: In two hyperinsulinism expert centers, 75 CHI patients were included (Russian, n = 33, referred non-Scandinavian, treated in Denmark n = 27, Scandinavian, n = 15). Hospital files were reviewed. At follow-up, neurodevelopmental impairment and neurodevelopmental, cognitive and motor function scores were assessed. RESULTS: Median (range) age at follow-up was 3.7 years (3.3 months-18.2 years). Neurodevelopmental impairment was seen in 35 (47%). Impairment was associated with abnormal brain magnetic resonance imaging (MRI); odds ratio (OR) (95% CI) 15.0 (3.0-74.3), p = 0.001; lowest recorded blood glucose ≤1 mmol/L; OR 3.8 (1.3-11.3), p = 0.015, being non-Scandinavian patient, OR 3.8 (1.2-11.9), p = 0.023; and treatment delay from first symptom to expert center >5 days; OR 4.0 (1.0-16.6), trend p = 0.05. In multivariate analysis (n = 31) for early predictors with exclusion of brain MRI, treatment delay from first symptom to expert center >5 days conferred a significantly increased risk of neurodevelopment impairment, adjusted OR (aOR) 15.6 (1.6-146.7), p = 0.016, while lowest blood glucose ≤1 mmol/L had a trend toward increased risk, aOR 3.5 (1.1-14.3), p = 0.058. No associations for early vs. late disease onset, KATP-channel mutations, disease severity, focal vs. diffuse disease, or age at follow-up were seen in uni- or multivariate analysis. CONCLUSION: Not only very low blood glucose, but also insufficient treatment as expressed by delay until expert center hospitalization, increased the risk of neurodevelopmental impairment. This novel finding calls for improvements in spread of knowledge about CHI among health-care personnel and rapid contact with an expert CHI center on suspicion of CHI.

The use of instrumented gait analysis for individually tailored interdisciplinary interventions in children with cerebral palsy: a randomised controlled trial protocol.

BACKGROUND: Children with cerebral palsy (CP) often have an altered gait. Orthopaedic surgery, spasticity management, physical therapy and orthotics are used to improve the gait. Interventions are individually tailored and are planned on the basis of clinical examinations and standardised measurements to assess walking ('care as usual'). However, these measurements do not describe features in the gait that reflect underlying neuro-musculoskeletal impairments. This can be done with 3-dimensional instrumented gait analysis (IGA). The aim of this study is to test the hypothesis that improvements in gait following individually tailored interventions when IGA is used are superior to those following 'care as usual'. METHODS/DESIGN: A prospective, single blind, randomised, parallel group study will be conducted. Children aged 5 to 8 years with spastic CP, classified at Gross Motor Function Classification System levels I or II, will be included. The interventions under investigation are: 1) individually tailored interdisciplinary interventions based on the use of IGA, and 2) 'care as usual'. The primary outcome is gait measured by the Gait Deviation Index. Secondary outcome measures are: walking performance (1-min walk test) and patient-reported outcomes of functional mobility (Pediatric Evaluation of Disability Inventory), health-related quality of life (The Pediatric Quality of Life Inventory Cerebral Palsy Module) and overall health, pain and participation (The Pediatric Outcome Data Collection Instrument). The primary endpoint for assessing the outcome of the two interventions will be 52 weeks after start of intervention. A follow up will also be performed at 26 weeks; however, exclusively for the patient-reported outcomes. DISCUSSION: To our knowledge, this is the first randomised controlled trial comparing the effects of an individually tailored interdisciplinary intervention based on the use of IGA versus 'care as usual' in children with CP. Consequently, the study will provide novel evidence for the use of IGA. TRIAL REGISTRATION: ClinicalTrials.gov NCT02160457 . Registered June 2, 2014.

[Neurodegeneration with brain iron accumulation]. / Neurodegeneration med jernakkumulation i hjernen

Neurodegeneration with brain iron accumulation (NBIA) is a heterogeneous group of syndromes. Whereas NBIA1 (panto-thenate kinase-associated neurodegeneration) has been known since 1922, some of the other diseases in the NBIA group have just been known for a few years. We present the case of a 16-year-old man who recently was diagnosed with NBIA4. He had had neurodegenerative symptoms since he was eight years old. The typical MRI findings in the basal ganglia were important in diagnosing NBIA. Furthermore gait analysis and specific genetic testing were performed.

[Febrile infection-related status epilepticus in a child after a common infection].

A 13-year-old boy developed seizures and intractable status epilepticus a week after having had a sore throat. Ketogenic diet possibly had some effect. Antibodies to calmodulin dependent protein kinase II were found and could possibly suggest an immunologic aetiology.

[Early-onset epileptic encephalopathy caused by CDKL5 mutation].

Two girls suffering from early-onset epileptic encephalopathy are described. Both girls had changes involving the gene CDKL5. They both had seizures in the first weeks of life and normal EEG interictally. Both developed infantile spasms and severe developmental defect. The epilepsy was difficult to treat.

[Facial angiofibromas associated to tuberous sclerosis treated with topical sirolimus]. / Faciale angiofibromer ved tuberøs sklerose behandlet med sirolimussalve.

We present a five-year-old boy with facial angiofibromas associated to tuberous sclerosis successfully treated with topical sirolimus 0.4% applied three times a week for six months. After six months we observed a nearly complete resolution of facial angiofibromas. The blood levels of sirolimus remained under a detectable limit and no side-effects were observed. Topically applied sirolimus seems to be a safe and effective alternative to surgery or laser therapy.

[Genetic causes of infantile spasms--a systematic review]. / Genetisk udredning ved infantile spasmer.

Infantile spasms are a symptom of a severe epileptic encephalopathy. It is important to determine the aetiology for a child's disease. When a standard programme for evaluating the aetiology of the infantile spasms is unsuccessful genetic causes should be considered. We suggest array CGH as the first-line analysis and present an overview of relevant present possibilities for genetic testing.

[Selenoprotein-related muscular dystrophy]. / Selenoproteinrelateret muskeldystrofi.

A nine year-old girl with selenoprotein-related muscular dystrophy was diagnosed. The primary symptom was weak neck muscles. During childhood she developed a rigid spine and over a period of a few years a severe scoliosis. She was compound heterozygote for a mutation in the SEPN1 gene. Experimental treatment with N-acetylcystein for a period of two years was initiated.

Effect of a clown's presence at botulinum toxin injections in children: a randomized, prospective study.

BACKGROUND: The effect of the presence of a hospital clown during pediatric procedures has rarely been evaluated. In a pediatric ward, botulinum toxin injection is a painful procedure and a stressful experience for the child. We undertook a study of the effect of the presence of a hospital clown on children treated with botulinum toxin in an outpatient setting. METHODS: In total, 60 children, the majority of whom had spastic cerebral palsy, were subjected to a total of 121 botulinum toxin treatment sessions. Thirty-two children were being treated for the first time. During a 2-year period, we enrolled 121 treatment sessions prospectively, and the children were randomized to either the presence of a female clown during treatment or to no presence of a clown. The duration of the child's crying during the procedure was used as an indicator of the effect of the presence of a clown. RESULTS: The effect of the clown was significantly related to patient gender. Girls were found to have a significantly shorter period of crying when the clown was present. For children younger than 8 years, the effect on boys was negative. Children treated for the first time did not appear to benefit from the presence of the clown, and showed no difference in effect between genders. CONCLUSION: No effect of the clown was documented for children being treated for the first time. At repeat treatments, we saw a positive effect of the female clown in relation to girls, and a negative effect on boys younger than 8 years of age.

[Metformin treatment causes persisting lactic acidosis after cardiac arrest]. / Metforminbehandling giver vedvarende laktatacidose efter hjertestop.

Metformin associated lactic acidosis (MALA) is a rare condition with a prevalence of 3 per 100,000 patient-years. The reported mortality is about 50%. We describe a case of MALA in a 61-year-old obese, type II diabetic male who suffered a sudden cardiac arrest. After resuscitation, the patient developed severe lactic acidosis requiring continuous renal replacement therapy. The patient died within seven days from multiorgan failure. MALA should be suspected in therapy-resistant lactic acidosis. Haemofiltration/haemodialysis will correct acidosis and clear metformin.

[Epilepsy treatment by vagus nerve stimulation]. / Behandling af epilepsi ved stimulation af nervus vagus.

Epilepsy is a common neurological disorder, and between one fourth and one third of the patients do not obtain seizure freedom after treatment with antiepileptic drugs. If the epileptic seizures in such patients have severe consequences, the patients should be assessed for epilepsy surgery. In case epilepsy surgery is not feasible, vagus nerve stimulation (VNS) should be offered. VNS seems to have an effect in all epilepsy syndromes and seizure types. VNS is generally well-tolerated, and may even improve mood and quality of life. Many more epilepsy patients in Denmark should be offered VNS.