Prospective cohort study for identification of underlying genetic causes in neonatal encephalopathy using whole-exome sequencing

A possible genetic predisposition to suspected hypoxic-ischaemic encephalopathy

Within the last decade, several studies have explored whether there might be a genetic component in hypoxic-ischaemic encephalopathy (HIE) that influences susceptibility to or outcomes following hypoxic-ischaemic injury. This review provides a comprehensive overview of the findings to date from published studies investigating the genetics of HIE. It also highlights some of the challenges faced by researchers, as well as recommendations for future research.

Neonatal Encephalopathy: Novel Phenotypes and Genotypes Identified by Genome Sequencing

Background and Objectives

Neonatal encephalopathy (NE) is characterized by an abnormal level of consciousness with or without seizures in the neonatal period. It affects 1-6/1,000 live term newborns. We applied genome sequencing (GS) in term newborns with NE to investigate the underlying genetic causes.

Methods

We enrolled term newborns according to inclusion/exclusion criteria during their Neonatal Intensive Care admission. We performed GS trio and applied bioinformatic tools. We developed pipelines for manual filters. We applied in silico prediction tools, protein 3D modeling, and functional characterization to assess the pathogenicity of variants.

Results

Seventeen newborns fulfilled inclusion criteria. We identified 12 variants in 10 genes. We classified 4 variants in PPP2R5D, BCOR, CFL2, and SCN2A (previously established disease genes) as pathogenic/likely pathogenic; 7 variants in DST (previously established disease gene), STAB2, CELF4, SORCS2, CTNND2, and ASTN1 (5 candidate genes) as variants of uncertain significance (VUS); and one variant in STAB2 as likely benign. The CELF4 and ASTN1 copy number variants (CNVs) resulted in structural changes in protein 3D models. The functional characterization of SORCS2 VUS revealed disruption of SorCS2 dimer formation and confirmed its pathogenicity. The functional characterization of STAB2 variants updated their characterization from VUS/likely benign to benign. The CTNND2 VUS resulted in a shift in 3D protein structure. We were not able to perform protein 3D modeling and functional characterization of two DST VUS. We are not certain whether CTNND2 and DST variants may be causative of NE in our study.

Discussion

The diagnostic rate of research GS was 41% in our prospective study. We broaden the phenotypic spectrum of PPP2R5D-associated Hogue-Janssens syndrome 1, CFL2-associated nemaline myopathy 7, and BCOR-associated oculo-facio-cardio-dental syndrome to include NE and/or neonatal seizures. We identified 3 candidate genes (SORCS2, CELF4, ASTN1) that may cause NE. We believe that protein 3D modeling is an important tool to assess the pathogenicity of CNVs and may advance the discoveries of novel genetic diseases. However, functional characterization of missense variants is essential for discoveries of novel genetic diseases. It seems that GS can help identify more candidate genes compared with ES.

The peripheral chemoreflex and fetal defenses against intrapartum hypoxic-ischemic brain injury at term gestation

Fetal hypoxemia is ubiquitous during labor and, when severe, is associated with perinatal death and long-term neurodevelopmental disability. Adverse outcomes are highly associated with barriers to care, such that developing countries have a disproportionate burden of perinatal injury. The prevalence of hypoxemia and its link to injury can be obscure, simply because the healthy fetus has robust coordinated defense mechanisms, spearheaded by the peripheral chemoreflex, such that hypoxemia only becomes apparent in the minority of cases associated with stillbirth, severe metabolic acidemia or adverse neurodevelopmental outcomes. This represents only the extreme end of the spectrum, when defense mechanisms have failed due to severe/prolonged hypoxemia, or the fetal defenses are compromised by additional risk factors. Understanding the fetal defenses to hypoxemia and when the fetus begins to decompensate is crucial to understanding perinatal health and disease, by linking antenatal health, intrapartum events, the neonatal trajectory and ultimately life-long neurodevelopmental health.

Genetic Diagnosis in Neonatal Encephalopathy With Hypoxic Brain Damage Using Targeted Gene Panel Sequencing

BACKGROUND AND PURPOSE

Neonatal encephalopathy (NE) is a neurological syndrome that presents with severe neurological impairments and complications. Hypoxic-ischemic encephalopathy is a major contributor to poor outcomes, being responsible for 50%-80% of admissions to neonatal intensive care units. However, some cases of NE accompanied by hypoxic brain damage cannot be solely attributed to hypoxia-ischemia. We aimed to identify diverse pathogenic genetic variations that may be associated with cases of NE accompanied by hypoxic brain damage rather than hypoxia-ischemia.

METHODS

We collected data from 34 patients diagnosed with NE accompanied by hypoxic brain damage over a 10-year period. Patients with the following specific conditions were excluded: 1) premature birth (<32 weeks), 2) no history of hypoxic events, 3) related anomalies, 4) neonatal infections, 5) antenatal or perinatal obstetrical complications, 6) severe hypoxia due to other medical conditions, and 7) early death (within 1 week). A comprehensive review of clinical and radiological features was conducted.

RESULTS

A genetic diagnosis was made in 11 (32.4%) patients, with pathogenic variants being identified in the following 9 genes: CACNA1A (n=2), KCNQ2 (n=2), SCN2A (n=1), SCN8A (n=1), STXBP1 (n=1), NSD1 (n=1), PURA (n=1), ZBTB20 (n=1), and ENG (n=1). No specific treatment outcomes or clinical features other than preterm birth were associated with the results of the genetic analyses. Personalized treatments based on the results of genetic tests were attempted, such as the administration of sodium-channel blockers in patients with KCNQ2 or SCN8A variants and the implementation of a ketogenic diet in patients with STXBP1 or SCN2A mutations, which demonstrated some degree of effectiveness in these patients.

CONCLUSIONS

Genetic analyses may help in diagnosing the underlying etiology of NE and concurrent hypoxic brain damage, irrespective of the initial clinical features.

Causes and Terminology in Neonatal Encephalopathy: What is in a Name? Neonatal Encephalopathy, Hypoxic-ischemic Encephalopathy or Perinatal Asphyxia

Neurologic depression in term/near-term neonates (neonatal encephalopathy, NE) is uncommon with modern obstetric care. Asphyxial birth, with or without co-factors, accounts for a minority of NE, while maldevelopment (congenital malformations, growth aberrations, genetic, metabolic and placental abnormalities) plays an enlarging role in identifying etiologic subgroups of NE. The terms NE and hypoxic-ischemic encephalopathy (HIE) have not been employed uniformly, hampering research and clinical care. The authors propose the term NE as an early working-diagnosis, to be supplemented by a diagnosis of NE due to HIE or to other factors, as a final diagnosis once workup is complete.

Clinical exome sequencing uncovers genetic disorders in neonates with suspected hypoxic-ischemic encephalopathy: A retrospective analysis

Hypoxic-ischemic encephalopathy (HIE) occurs in up to 7 out of 1000 births and accounts for almost a quarter of neonatal deaths worldwide. Despite the name, many newborns with HIE have little evidence of perinatal hypoxia. We hypothesized that some infants with HIE have genetic disorders that resemble encephalopathy. We reviewed genetic results for newborns with HIE undergoing exome or genome sequencing at a clinical laboratory (2014-2022). Neonates were included if they had a diagnosis of HIE and were delivered ≥35 weeks. Neonates were excluded for cardiopulmonary pathology resulting in hypoxemia or if neuroimaging suggested postnatal hypoxic-ischemic injury. Of 24 patients meeting inclusion criteria, six (25%) were diagnosed with a genetic condition. Four neonates had variants at loci linked to conditions with phenotypic features resembling HIE, including KIF1A, GBE1, ACTA1, and a 15q13.3 deletion. Two additional neonates had variants in genes not previously associated with encephalopathy, including DUOX2 and PTPN11. Of the six neonates with a molecular diagnosis, two had isolated HIE without apparent comorbidities to suggest a genetic disorder. Genetic diagnoses were identified among neonates with and without sentinel labor events, abnormal umbilical cord gasses, and low Apgar scores. These results suggest that genetic evaluation is clinically relevant for patients with perinatal HIE.

Genetic and Congenital Anomalies in Infants With Hypoxic-Ischemic Encephalopathy

BACKGROUND

Infants with hypoxic ischemic encephalopathy (HIE) may have underlying conditions predisposing them to hypoxic-ischemic injury during labor and delivery. It is unclear how genetic and congenital anomalies impact outcomes of HIE.

METHODS

Infants with HIE enrolled in a phase III trial underwent genetic testing when clinically indicated. Infants with known genetic or congenital anomalies were excluded. The primary outcome, i.e., death or neurodevelopmental impairment (NDI), was determined at age two years by a standardized neurological examination, Bayley Scales of Infant Development, Third Edition (BSID-III), and the Gross Motor Function Classification Scales. Secondary outcomes included cerebral palsy and BSID-III motor, cognitive, and language scores at age two years.

RESULTS

Of 500 infants with HIE, 24 (5%, 95% confidence interval 3% to 7%) were diagnosed with a genetic (n = 15) or congenital (n = 14) anomaly. Infants with and without genetic or congenital anomalies had similar rates of severe encephalopathy and findings on brain magnetic resonance imaging. However, infants with genetic or congenital anomalies were more likely to have death or NDI (75% vs 50%, P = 0.02). Among survivors, those with a genetic or congenital anomaly were more likely to be diagnosed with cerebral palsy (32% vs 13%, P = 0.02), and had lower BSID-III scores in all three domains than HIE survivors without such anomalies.

CONCLUSIONS

Among infants with HIE, 5% were diagnosed with a genetic or congenital anomaly. Despite similar clinical markers of HIE severity, infants with HIE and a genetic or congenital anomaly had worse neurodevelopmental outcomes than infants with HIE alone.

[Early differential diagnosis and restorative treatment of cerebral palsy]

The article is devoted to an urgent problem of modern neurology - early diagnosis and complex restorative treatment of cerebral palsy (cerebral palsy). Etiological factors and pathogenetic aspects of the formation of various forms of cerebral palsy are considered in detail, as well as modern possibilities of differential diagnosis in children of the first years of life of cerebral palsy and a wide range of pathological conditions (somatic, endocrine, hereditary-conditioned, including hereditary-metabolic and neuromuscular diseases). The leading directions of complex rehabilitation of cerebral palsy are widely presented, taking into account modern standards and clinical recommendations. The high efficacy of the drug Cortexin has been shown, due to its positive multimodal action (stimulation of the processes of neuropreparation, neuroprotection, neuroplasticity) in the treatment of motor, cognitive and autonomic disorders in children with perinatal lesions of the central nervous system and cerebral palsy.

Newly discovered variants in unexplained neonatal encephalopathy

BACKGROUND

The genetic background of neonatal encephalopathy (NE) is complicated and early diagnosis is beneficial to optimizing therapeutic strategy for patients.

METHODS

NE Patients with unclear etiology received regular clinical tests including ammonia test, metabolic screening test, amplitude-integrated electroencephalographic (aEEG) monitoring, brain Magnetic Resonance Imaging (MRI) scanning, and genetic test. The protein structure change was predicted using Dynamut2 and RoseTTAFold.

RESULTS

15 out of a total of 113 NE Patients were detected with newly reported pathogenic variants. In this sub-cohort, (1) seizure was the primary initial symptoms; (2) four patients had abnormal metabolic screening results, and two of them were also diagnosed with excessive blood ammonia concentration; (3) the brain MRI results were irregular in three infants and the brain waves were of moderate-severe abnormality in about a half of the patients. The novel pathogenic variants discovered in this study belonged to 12 genes, and seven of them were predicted to introduce a premature translation termination. In-silicon predictions showed that four variants were destructive to the protein structure of KCNQ2.

CONCLUSION

Our study expands the mutation spectrum of genes associated with NE and introduces new evidence for molecular diagnosis in this newborn illness.

Characteristics, Genetic Testing, and Diagnoses of Infants with Neonatal Encephalopathy Not Due to Hypoxic Ischemic Encephalopathy: A Cohort Study

OBJECTIVE

To characterize the presentation and evaluation of infants with neonatal encephalopathy (NE) not due to hypoxic-ischemic encephalopathy (non-HIE NE) and to describe the genetic abnormalities identified.

STUDY DESIGN

Retrospective cohort study of 193 non-HIE NE neonates admitted to a level IV NICU from 2015 through 2019. For changes in testing over time, Cochrane-Armitage test for trend was used with a Bonferroni-corrected P-value, and comparison between groups was performed using Fisher exact test.

RESULT

The most common symptom of non-HIE NE was abnormal tone in 47% (90/193). Ten percent (19/193) died prior to discharge, and 48% of survivors (83/174) required medical equipment at discharge. Forty percent (77/193) underwent genetic testing as an inpatient. Of 52 chromosomal studies, 54 targeted tests, and 16 exome sequences, 10%, 41%, and 69% were diagnostic, respectively, with no difference in diagnostic rates between infants with and without an associated congenital anomaly and/or dysmorphic feature. Twenty-eight genetic diagnoses were identified.

CONCLUSIONS

Neonates with non-HIE NE have high rates of morbidity and mortality and may benefit from early genetic testing, even in the absence of other exam findings. This study broadens our knowledge of genetic conditions underlying non-HIE NE, which may enable families and care teams to anticipate the needs of the individual, allow early initiation of targeted therapies, and facilitate decisions surrounding goals of care.

Mimicking Hypoxic-Ischemic Encephalopathy in a Newborn with 21q Deletion Originating from Ring Chromosome 21

Partial deletion of the long arm (q) in chromosome 21 is an extremely rare condition with various phenotypes, including microcephaly, neurodevelopmental delay, dysmorphic features, and epileptic seizures. Neonatal hypoxic-ischemic encephalopathy (HIE) is an encephalopathy associated with a hypoxic-ischemic event in the brain where seizures usually occur in the earliest days of life. Neonatal encephalopathy is a distinct entity resulting from metabolic disorders, congenital infections or genetic abnormalities that could often mimic HIE features, leading to a misdiagnosis of HIE. Here, we present a case of a newborn who was initially misdiagnosed with HIE due to HIE-like features, and eventually was diagnosed to have a de novo ring chromosome 21 with 21q microdeletion. Clinical findings, including severe hypotonia with respiratory/feeding difficulties and intractable seizures, and radiologic findings of ischemic encephalopathy were discovered. Subsequent atypical findings of the clinical presentation ultimately led to her undergoing genetic testing confirming that she had a neonatal encephalopathy with a genetic abnormality. Our case highlights the importance of identifying non-HI neonatal encephalopathy by careful and structured evaluation for current history with a clinical course and a multidisciplinary approach including genetic testing, to provide an accurate diagnosis, treat curable inherited disorders, and develop future genetic counseling.

Identifying Genetic Susceptibility in Neonates With Hypoxic-Ischemic Encephalopathy: A Retrospective Case Series

Neonatal hypoxic-ischemic encephalopathy is a clinical phenomenon that often results from perinatal asphyxia. To mitigate secondary neurologic injury, prompt initial assessment and diagnosis is needed to identify patients eligible for therapeutic hypothermia. However, occasionally neonates present with a clinical picture of hypoxic-ischemic encephalopathy without significant risk factors for perinatal asphyxia. We hypothesized that in patients with genetic abnormalities, the clinical manifestation of those abnormalities may overlap with hypoxic-ischemic encephalopathy criteria, potentially contributing to a causal misattribution. We reviewed 210 charts of infants meeting local protocol criteria for moderate to severe hypoxic-ischemic encephalopathy in neonatal intensive care units in Calgary, Alberta. All patients that met criteria for therapeutic hypothermia were eligible for the study. Data were collected surrounding pregnancy and birth histories, as well as any available genetic or metabolic testing including microarray, gene panels, whole-exome sequencing, and newborn metabolic screens. Twenty-eight patients had genetic testing such as microarray, whole-exome sequencing, or a gene panel, because of clinical suspicion. Ten of 28 patients had genetic mutations, including CDKL5, pyruvate dehydrogenase, CFTR, CYP21A2, ISY1, KIF1A, KCNQ2, SCN9A, MTFMT, and NPHP1. All patients lacked significant risk factors to support a moderate to severe hypoxic-ischemic encephalopathy diagnosis. Treatment was changed in 2 patients because of confirmed genetic etiology. This study demonstrates the importance of identifying genetic comorbidities as potential contributors to a hypoxic-ischemic encephalopathy phenotype in neonates. Early identification of clinical factors that support an alternate diagnosis should be considered when the patient's clinical picture is not typical of hypoxic-ischemic encephalopathy and could aid in both treatment decisions and outcome prognostication.

CUL4B-associated epilepsy: Report of a novel truncating variant promoting drug-resistant seizures and systematic review of the literature

BACKGROUND

Cabezas syndrome is a rare X-linked disease caused by mutations in CUL4B and characterized by developmental delay/intellectual disability, somatic dysmorphisms, behavioural disorder, ataxia/tremors. Although seizures have been formerly reported, their clinical semiology, EEG features and long-term outcome are largely unknown.

PURPOSE

This study aims to expand knowledge on epilepsy associated with Cabezas syndrome and to understand whether different types of variants in the CUL4B gene or brain MRI abnormalities may influence seizure onset and epilepsy course.

METHODS

With this in mind, we characterised the epileptic phenotype of a 17-year-old adolescent harbouring a CUL4B novel variant and performed a systematic literature review of CUL4B-associated seizures, analysing mutation types and neuroimaging features as epilepsy predictors.

RESULTS

Our case observation indicates that CUL4B-associated epilepsy may also be drug-resistant and persist beyond infancy. Literature analysis shows that 43% of CUL4B patients develop seizures, with no statistically significant differences in epilepsy development according to mutation type and neuroimaging features.

CONCLUSION

Our study extends knowledge of CUL4B-associated epilepsy, offering new insights into disease progression.

GNAO1-related neurodevelopmental disorder: Literature review and caregiver survey

Background

GNAO1-related neurodevelopmental disorder is a heterogeneous condition characterized by hypotonia, developmental delay, epilepsy, and movement disorder. This study aims to better understand the spectrum of epilepsy associated with GNAO1 variants and experience with anti-seizure medications, and to review published epilepsy phenotypes in GNAO1.

Methods

An online survey was distributed to caregivers of individuals diagnosed with GNAO1 pathogenic variants, and a literature review was conducted.

Results

Fifteen respondents completed the survey with the median age of 39 months, including a novel variant p.Q52P. Nine had epilepsy - six had onset in the first week of life, three in the first year of life - but two reported no ongoing seizures. Seizure types varied. Individuals were taking a median of 3 seizure medications without a single best treatment. Our cohort was compared to a literature review of epilepsy in GNAO1. In 86 cases, 38 discrete variants were described; epilepsy is reported in 53 % cases, and a developmental and epileptic encephalopathy in 36 %.

Conclusions

While GNAO1-related epilepsy is most often early-onset and severe, seizures may not always be drug resistant or lifelong. Experience with anti-seizure medications is varied. Certain variant "hotspots" may correlate with epilepsy phenotype though genotype-phenotype correlation is poorly understood.

Better and faster is cheaper

The rapid pace of advancement in genomic sequencing technology has recently reached a new milestone, with a record-setting time to molecular diagnosis of a mere 8 h. The catalyst behind this achievement is the accumulation of evidence indicating that quicker results more often make an impact on patient care and lead to healthcare cost savings. Herein, we review the diagnostic and clinical utility of rapid whole genome and rapid whole exome sequencing, the associated reduction in healthcare costs, and the relationship between these outcome measures and time-to-diagnosis.

Risk factors for neonatal encephalopathy in late preterm and term singleton births in a large California birth cohort

OBJECTIVE

The objective was to investigate maternal and pregnancy characteristics associated with neonatal encephalopathy (NE).

STUDY DESIGN

We queried an administrative birth cohort from California between 2011 and 2017 to determine the association between each factor and NE with and without hypothermia treatment.

RESULTS

From 3 million infants born at 35 or more weeks of gestation, 6,857 cases of NE were identified (2.3 per 1000 births), 888 (13%) received therapeutic hypothermia. Risk factors for NE were stronger among cases receiving hypothermia therapy. Substance-related diagnosis, preexisting diabetes, preeclampsia, and any maternal infection were associated with a two-fold increase in risk. Maternal overweight/obesity, nulliparity, advanced maternal age, depression, gestational diabetes or hypertension, and short or long gestations also predicted NE. Young maternal age, Asian race and Hispanic ethnicity, and cannabis-related diagnosis lowered risk of NE.

CONCLUSIONS

By disseminating these results, we encourage further interrogation of these perinatal factors.

Neonatal encephalopathy: Etiologies other than hypoxic-ischemic encephalopathy

Neonatal encephalopathy (NE) describes the clinical syndrome of a newborn with abnormal brain function that may result from a variety of etiologies. HIE should be distinguished from neonatal encephalopathy due to other causes using data gathered from the history, physical and neurological exam, and further investigations. Identifying the underlying cause of encephalopathy has important treatment implications. This review outlines conditions that cause NE and may be mistaken for HIE, along with their distinguishing clinical features, pathophysiology, investigations, and treatments. NE due to brain malformations, vascular causes, neuromuscular causes, genetic conditions, neurogenetic disorders and inborn errors of metabolism, central nervous system (CNS) and systemic infections, and toxic/metabolic disturbances are discussed.

Comparative Proteomic Characterization of Ventral Hippocampus in Susceptible and Resilient Rats Subjected to Chronic Unpredictable Stress

Chronic stress is an essential factor leading to depression. However, there exist individual differences in people exposed to the same stressful stimuli. Some people display negative psychology and behavior, while others are normal. Given the importance of individual difference, finding differentially expressed proteins in stress-resistant and stress-susceptible groups has great significance for the study of pathogenesis and treatment of depression. In this study, stress-susceptible rats and stress-resilient rats were first distinguished by sucrose preference test. These stress-susceptible rats also displayed depression-like behaviors in forced swimming test and open field test. Then, we employed label-free quantitative proteomics to analyze proteins in the ventral hippocampus. There were 4,848 proteins totally identified. Based on statistical analysis, we found 276 differentially expressed proteins. Bioinformatics analysis revealed that the biological processes of these differential proteins were related to mitochondrion organization, protein localization, coenzyme metabolic process, cerebral cortex tangential migration, vesicle-mediated transport, and so on. The KEGG pathways were mainly involved in metabolic pathways, axon guidance, autophagy, and tight junction. Furthermore, we ultimately found 20 stress-susceptible proteins and two stress-resilient proteins. These stress-related proteins could not only be potential biomarkers for depression diagnosis but also contribute to finding new therapeutic targets and providing personalized medicine.

Neuromonitoring in Neonatal-Onset Epileptic Encephalopathies

Considering the wide spectrum of etiologies of neonatal-onset epileptic encephalopathies (EE) and their unfavorable consequences for neurodevelopmental prognoses, neuromonitoring at-risk neonates is increasingly important. EEG is highly sensitive for early identification of electrographic seizures and abnormal background activity. Amplitude-integrated EEG (aEEG) is recommended as a useful bedside monitoring method but as a complementary tool because of methodical limitations. It is of special significance in monitoring neonates with acute symptomatic as well as structural, metabolic and genetic neonatal-onset EE, being at high risk of electrographic-only and prolonged seizures. EEG/aEEG monitoring is established as an adjunctive tool to confirm perinatal hypoxic-ischemic encephalopathy (HIE). In neonates with HIE undergoing therapeutic hypothermia, burst suppression pattern is associated with good outcomes in about 40% of the patients. The prognostic specificity of EEG/aEEG is lower compared to cMRI. As infants with HIE may develop seizures after cessation of hypothermia, recording for at least 24 h after the last seizure is recommended. Progress in the identification of genetic etiology of neonatal EE constantly increases. However, presently, no specific EEG changes indicative of a genetic variant have been characterized, except for individual variants associated with typical EEG patterns (e.g., KCNQ2, KCNT1). Long-term monitoring studies are necessary to define and classify electro-clinical patterns of neonatal-onset EE.

Genetic Testing in Epilepsy

Because of next-generation sequencing and the discovery of many new causative genes, genetic testing in epilepsy patients has become widespread. Pathologic variants resulting in epilepsy cause a variety of changes that can be broadly classified into syndromic disorders (i.e., chromosomal abnormalities), metabolic disorders, brain malformations, and abnormal cellular signaling. Here, we review the available genetic testing, reasons to pursue genetic testing, common genetic causes of epilepsy, the data behind what patients are found to have genetic epilepsies based on current testing, and discussing these results with patients. We propose an algorithm for testing patients with epilepsy to maximize yield and limit costs based on their phenotype (including electroencephalography and magnetic resonance imaging findings), age of seizure onset, and presence of other neurologic comorbidities. Being able to discern which type of genetic testing to order, using that information to give targeted and cost-effective patient care, and interpreting results accurately will be a crucial skill for the modern neurologist.

Genome-first approach for the characterization of a complex phenotype with combined NBAS and CUL4B deficiency

Biallelic variants in neuroblastoma-amplified sequence (NBAS) cause an extremely broad spectrum of phenotypes. Clinical features range from isolated recurrent episodes of liver failure to multisystemic syndrome including short stature, skeletal osteopenia and dysplasia, optic atrophy, and a variable immunological, cutaneous, muscular, and neurological abnormalities. Hemizygous variants in CUL4B cause syndromic X-linked intellectual disability characterized by limitations in intellectual functions, developmental delays in gait, cognitive, and speech functioning, and other features including short stature, dysmorphism, and cerebral malformations. In this study, we report on a 4.5-month-old preterm infant with a complex phenotype mainly characterized by placental-related severe intrauterine growth restriction, post-natal growth failure with spontaneous bone fractures, which led to a suspicion of osteogenesis imperfecta, and lethal bronchopulmonary dysplasia with pulmonary hypertension. Whole exome sequencing identified compound heterozygosity for a known frameshift and a novel missense variant in NBAS and hemizygosity for a known CUL4B nonsense mutation. In vitro functional studies on the novel NBAS missense substitution demonstrated altered Golgi-to-endoplasmic reticulum retrograde vesicular trafficking and reduced collagen secretion, likely explaining part of the patient's phenotype. We also provided a comprehensive overview of the phenotypic features of NBAS and CUL4B deficiency, thus updating the recently emerging NBAS genotype-phenotype correlations. Our findings highlight the power of a genome-first approach for an early diagnosis of complex phenotypes.

Clinical features and underlying genetic causes in neonatal encephalopathy: A large cohort study

This study aimed to investigate the potential genetic causes of neonatal encephalopathy (NE) in a large cohort of Chinese patients. We included 366 neonates with encephalopathy. Whole exome sequencing was performed to assess the potential molecular defects. In this study, 43 patients (11.7%) were identified with pathogenic or likely pathogenic variants and 10 patients (2.7%) carried variants with unknown significance. Compared with patients without genetic findings (28.9%), patients with genetic findings (96.2%) displayed a significant higher incidence of seizure (P = .0009); however, a lower frequency of abnormal magnetic resonance imaging (MRI) results (P < .0001). Epileptic encephalopathy related genes account for nearly half (46.4%) of all genetic defects of NE with seizures. Follow-up results revealed genetic diagnosis, seizure and severe abnormal electroencephalograph results were significantly associated with high risk of developmental delay (P < .05). This study increases the understanding of genetic contribution to NE. Our findings suggest that the full-term NE patients with seizure, the greater the possibility of genetic diseases. However, for newborns especially the preterm babies with abnormal MRI findings, there is smaller possibility of genetic diseases. NE caused from genetic diseases have poor prognosis, and intensive intervention and follow-up is necessary for these newborns.

Mice with GNAO1 R209H Movement Disorder Variant Display Hyperlocomotion Alleviated by Risperidone

Neurodevelopmental disorder with involuntary movements (Online Mendelian Inheritance in Man: 617493) is a severe, early onset neurologic condition characterized by a delay in psychomotor development, hypotonia, and hyperkinetic involuntary movements. Heterozygous de novo mutations in the GNAO1 gene cause neurodevelopmental disorder with involuntary movements. Gα o, the gene product of GNAO1, is the alpha subunit of Go, a member of the heterotrimeric Gi/o family of G proteins. Go is found abundantly throughout the brain, but the pathophysiological mechanisms linking Gα o functions to clinical manifestations of GNAO1-related disorders are still poorly understood. One of the most common mutant alleles among the GNAO1 encephalopathies is the c.626G>A or p.Arg209His (R209H) mutation. We developed heterozygous knock-in Gnao1 +/R209H mutant mice using CRISPR/Cas9 methodology to assess whether a mouse model could replicate aspects of the neurodevelopmental disorder with involuntary movements clinical pattern. Mice carrying the R209H mutation exhibited increased locomotor activity and a modest gait abnormality at 8-12 weeks. In contrast to mice carrying other mutations in Gnao1, the Gnao1 +/R209H mice did not show enhanced seizure susceptibility. Levels of protein expression in multiple brain regions were unchanged from wild-type (WT) mice, but the nucleotide exchange rate of mutant R209H Gα o was 6.2× faster than WT. The atypical neuroleptic risperidone has shown efficacy in a patient with the R209H mutation. It also alleviated the hyperlocomotion phenotype observed in our mouse model but suppressed locomotion in WT mice as well. In this study, we show that Gnao1 +/R209H mice mirror elements of the patient phenotype and respond to an approved pharmacological agent. SIGNIFICANCE STATEMENT: Children with de novo mutations in the GNAO1 gene may present with movement disorders with limited effective therapeutic options. The most common mutant variant seen in children with GNAO1-associated movement disorder is R209H. Here we show, using a novel Gnao1 +/R209H mouse, that there is a clear behavioral phenotype that is suppressed by risperidone. However, risperidone also affects wild-type mouse activity, so its effects are not selective for the GNAO1-associated movement disorder.

EEG Monitoring of the Epileptic Newborn

PURPOSE OF REVIEW

Although differentiating neonatal-onset epilepsies from acute symptomatic neonatal seizures has been increasingly recognized as crucial, existing guidelines, and recommendations on EEG monitoring are mainly based on acute symptomatic seizures, especially secondary to hypoxic-ischemic encephalopathy. We aimed to narratively review current knowledge on neonatal-onset epilepsies of genetic, metabolic, and structural non-acquired origin, with special emphasis on EEG features and monitoring.

RECENT FINDINGS

A wide range of rare conditions are increasingly described, reducing undiagnosed cases. Although distinguishing features are identifiable in some, how to best monitor and detect less described etiologies is still an issue. A comprehensive approach considering onset, seizure evolution, ictal semiology, clinical, laboratory, EEG, and neuroimaging data is key to diagnosis. Phenotypic variability prevents precise recommendations, but a solid, consistent method moving from existing published guidelines helps in correctly assessing these newborns in order to provide better care, especially in view of expanding precision therapies.

Systematic comparison of somatic variant calling performance among different sequencing depth and mutation frequency

In the past decade, treatments for tumors have made remarkable progress, such as the successful clinical application of targeted therapies. Nowadays, targeted therapies are based primarily on the detection of mutations, and next-generation sequencing (NGS) plays an important role in relevant clinical research. The mutation frequency is a major problem in tumor mutation detection and increasing sequencing depth is a widely used method to improve mutation calling performance. Therefore, it is necessary to evaluate the effect of different sequencing depth and mutation frequency as well as mutation calling tools. In this study, Strelka2 and Mutect2 tools were used in detecting the performance of 30 combinations of sequencing depth and mutation frequency. Results showed that the precision rate kept greater than 95% in most of the samples. Generally, for higher mutation frequency (≥20%), sequencing depth ≥200X is sufficient for calling 95% mutations; for lower mutation frequency (≤10%), we recommend improving experimental method rather than increasing sequencing depth. Besides, according to our results, although Strelka2 and Mutect2 performed similarly, the former performed slightly better than the latter one at higher mutation frequency (≥20%), while Mutect2 performed better when the mutation frequency was lower than 10%. Besides, Strelka2 was 17 to 22 times faster than Mutect2 on average. Our research will provide a useful and comprehensive guideline for clinical genomic researches on somatic mutation identification through systematic performance comparison among different sequencing depths and mutation frequency.

Genetic Aspects of Pathogenesis of Congenital Spastic Cerebral Paralysis

Congenital spastic cerebral palsy (СР) is a large group of non-progressive disorders of the nervous system. The basis of the pathogenesis of these conditions is considered the impact of many factors. The clinical diversity of the disease and the syndromic principle of classification determine the existing uncertainties in the diagnosis of these diseases. The multifactorial nature of the underlying brain lesions is obvious and beyond doubt. The volume of information accumulated to date does not allow one to exclude the role and significance of the direct effect of acute asphyxiation in childbirth on a fetus normally formed during pregnancy, the role of infectious brain lesions, and disorders of neuronal migration. It is impossible to ignore the dependence of the clinical picture of the disease on what stage of ontogenesis the impact of the damaging agent occurs. As one of the pathogenetic factors, the genetic determinism of the phenotype of the clinical picture of a disease is fairly considered. This review focuses on the genetic aspects of the pathogenesis of this pathology. The information on monogenic mechanisms of inheritance is analyzed in detail. Such genetically determined mechanisms of pathogenesis as the inheritance of prerequisites for brain trauma in the perinatal period are considered separately. The new clinically significant variants of chromosomal mutations found in patients with CР are reviewed in detail,  the evidence of the influence of genetic factors on the development of cerebral palsy in the absence of a pronounced monogenic cause of the disease, obtained through twin studies, is reviewed.  Lit search of polymorphisms markers of predisposition to the development of cerebral palsy genes of the folate cycle, genes of glutamate receptors, the gene of apolipoprotein and of the gene for the transcription factor of oligodendrocytes (OLIG2) in Detail the role of epigenetic effects on the activity of genes coding for mitochondrial proteins.

Biallelic SCN2A Gene Mutation Causing Early Infantile Epileptic Encephalopathy: Case Report and Review

The voltage-gated sodium channel neuronal type 2 alpha subunit (Na_vα1.2) encoded by the SCN2A gene causes early infantile epileptic encephalopathy (EIEE) inherited in an autosomal dominant manner. Clinically, it has variable presentations, ranging from benign familial infantile seizures (BFIS) to severe EIEE. Diagnosis is achieved through molecular DNA testing of the SCN2A gene. Herein, we report on a 30-month-old Saudi girl who presented on the fourth day of life with EIEE, normal brain magnetic resonance imaging (MRI), normal electroencephalography (EEG), and well-controlled seizures. Genetic investigation revealed a novel homozygous missense mutation (c.5242A > G; p.Asn1748Asp) in the SCN2A gene (NM_001040142.1). This is the first reported autosomal recessive inheritance of a disease allele in the SCN2A and therefore expands the molecular and inheritance spectrum of the SCN2A gene defects.

Spectrum of neurodevelopmental disease associated with the GNAO1 guanosine triphosphate-binding region

OBJECTIVE

To characterize the phenotypic spectrum associated with GNAO1 variants and establish genotype-protein structure-phenotype relationships.

METHODS

We evaluated the phenotypes of 14 patients with GNAO1 variants, analyzed their variants for potential pathogenicity, and mapped them, along with those in the literature, on a three-dimensional structural protein model.

RESULTS

The 14 patients in our cohort, including one sibling pair, had 13 distinct, heterozygous GNAO1 variants classified as pathogenic or likely pathogenic. We attributed the same variant in two siblings to parental mosaicism. Patients initially presented with seizures beginning in the first 3 months of life (8/14), developmental delay (4/14), hypotonia (1/14), or movement disorder (1/14). All patients had hypotonia and developmental delay ranging from mild to severe. Nine had epilepsy, and nine had movement disorders, including dystonia, ataxia, chorea, and dyskinesia. The 13 GNAO1 variants in our patients are predicted to result in amino acid substitutions or deletions in the GNAO1 guanosine triphosphate (GTP)-binding region, analogous to those in previous publications. Patients with variants affecting amino acids 207-221 had only movement disorder and hypotonia. Patients with variants affecting the C-terminal region had the mildest phenotypes.

SIGNIFICANCE

GNAO1 encephalopathy most frequently presents with seizures beginning in the first 3 months of life. Concurrent movement disorders are also a prominent feature in the spectrum of GNAO1 encephalopathy. All variants affected the GTP-binding domain of GNAO1, highlighting the importance of this region for G-protein signaling and neurodevelopment.

Precision in pediatric epilepsy

Epilepsy in infants and children is one of the most common and devastating neurological disorders. In the past, we had a limited understanding of the causes of epilepsy in pediatric patients, so we treated pediatric epilepsy according to seizure type. Now with new tools and tests, we are entering the age of precision medicine in pediatric epilepsy. In this review, we use the new etiological classification system proposed by the International League Against Epilepsy to review the advances in the diagnosis of pediatric epilepsy, describe new tools to identify seizure foci for epilepsy surgery, and define treatable epilepsy syndromes.

Mouse models of GNAO1-associated movement disorder: Allele- and sex-specific differences in phenotypes

BACKGROUND

Infants and children with dominant de novo mutations in GNAO1 exhibit movement disorders, epilepsy, or both. Children with loss-of-function (LOF) mutations exhibit Epileptiform Encephalopathy 17 (EIEE17). Gain-of-function (GOF) mutations or those with normal function are found in patients with Neurodevelopmental Disorder with Involuntary Movements (NEDIM). There is no animal model with a human mutant GNAO1 allele.

OBJECTIVES

Here we develop a mouse model carrying a human GNAO1 mutation (G203R) and determine whether the clinical features of patients with this GNAO1 mutation, which includes both epilepsy and movement disorder, would be evident in the mouse model.

METHODS

A mouse Gnao1 knock-in GOF mutation (G203R) was created by CRISPR/Cas9 methods. The resulting offspring and littermate controls were subjected to a battery of behavioral tests. A previously reported GOF mutant mouse knock-in (Gnao1+/G184S), which has not been found in patients, was also studied for comparison.

RESULTS

Gnao1+/G203R mutant mice are viable and gain weight comparably to controls. Homozygotes are non-viable. Grip strength was decreased in both males and females. Male Gnao1+/G203R mice were strongly affected in movement assays (RotaRod and DigiGait) while females were not. Male Gnao1+/G203R mice also showed enhanced seizure propensity in the pentylenetetrazole kindling test. Mice with a G184S GOF knock-in also showed movement-related behavioral phenotypes but females were more strongly affected than males.

CONCLUSIONS

Gnao1+/G203R mice phenocopy children with heterozygous GNAO1 G203R mutations, showing both movement disorder and a relatively mild epilepsy pattern. This mouse model should be useful in mechanistic and preclinical studies of GNAO1-related movement disorders.

Genetics of neonatal-onset epilepsies

Although the majority of seizures in neonates are related to acute brain injury, a substantial minority are the first symptom of a neonatal-onset epilepsy often linked to a pathogenic genetic variant. Historically, studies on neonatal seizures including treatment response and long-term consequences have lumped all etiologies together. However, etiology has been consistently shown to be the most important determinant of outcome. In the past few years, an increasing number of monogenic disorders have been described and might explain up to a third of neonatal-onset epilepsy syndromes previously included under the umbrella of Ohtahara syndrome and early myoclonic encephalopathy. In this chapter, we define the concept of genetic epilepsy and review the classification. Then, we review the most relevant monogenic neonatal-onset epilepsies, detail their underlying pathophysiologic mechanisms, and present their electroclinical phenotypes. We highlight that, in some cases, such as neonates with KCNQ2 or KCNT1 gene mutations, the early recognition of the electroclinical phenotype can lead to targeted diagnostic testing and precision medicine treatment, enabling the possibility of improved outcome.

Phenomenology and clinical course of movement disorder in GNAO1 variants: Results from an analytical review

GNAO1 variants were recently discovered as causes of epileptic encephalopathies and heterogeneous syndromes presenting with movement disorders (MDs), whose phenomenology and clinical course are yet undefined. We herein focused on GNAO1-related MD, providing an analytical review of existing data to outline the main MD phenomenology and management, clinical evolution and genotype-phenotype correlations. Reviewing 41 previously published patients and assessing 5 novel cases, a comprehensive cohort of 46 patients was analyzed, reassuming knowledge about genotypes, phenotypes, disease course and treatment of this condition. GNAO1-related MD consisted of a severe early-onset hyperkinetic syndrome, with prominent chorea, dystonia and orofacial dyskinesia. Symptoms are poorly responsive to medical therapy and fluctuate, with critical and life-threatening exacerbations, such as status dystonicus. The presence of a choreiform MD appears to be predictive of a higher risk of movement disorder emergency. Surgical treatments are sometimes effective, although severe disabilities persist. Differently from the early infantile epileptic encephalopathy phenotype (associated with loss of function variants), no clear correlation between genotype and MD phenotype emerged, although some variants recurred more frequently, mainly affecting exons 6 and 7.

Postsynaptic movement disorders: clinical phenotypes, genotypes, and disease mechanisms

Movement disorders comprise a group of heterogeneous diseases with often complex clinical phenotypes. Overlapping symptoms and a lack of diagnostic biomarkers may hamper making a definitive diagnosis. Next-generation sequencing techniques have substantially contributed to unraveling genetic etiologies underlying movement disorders and thereby improved diagnoses. Defects in dopaminergic signaling in postsynaptic striatal medium spiny neurons are emerging as a pathogenic mechanism in a number of newly identified hyperkinetic movement disorders. Several of the causative genes encode components of the cAMP pathway, a critical postsynaptic signaling pathway in medium spiny neurons. Here, we review the clinical presentation, genetic findings, and disease mechanisms that characterize these genetic postsynaptic movement disorders.

Epilepsy genetics: Current knowledge, applications, and future directions

The rapid pace of disease gene discovery has resulted in tremendous advances in the field of epilepsy genetics. Clinical testing with comprehensive gene panels, exomes, and genomes are now available and have led to higher diagnostic rates and insights into the underlying disease processes. As such, the contribution to the care of patients by medical geneticists, neurogeneticists and genetic counselors are significant; the dysmorphic examination, the necessary pre- and post-test counseling, the selection of the appropriate next-generation sequencing-based test(s), and the interpretation of sequencing results require a care provider to have a comprehensive working knowledge of the strengths and limitations of the available testing technologies. As the underlying mechanisms of the encephalopathies and epilepsies are better understood, there may be opportunities for the development of novel therapies based on an individual's own specific genotype. Drug screening with in vitro and in vivo models of epilepsy can potentially facilitate new treatment strategies. The future of epilepsy genetics will also probably include other-omic approaches such as transcriptomes, metabolomes, and the expanded use of whole genome sequencing to further improve our understanding of epilepsy and provide better care for those with the disease.

A mechanistic review on GNAO1-associated movement disorder

Mutations in the GNAO1 gene cause a complex constellation of neurological disorders including epilepsy, developmental delay, and movement disorders. GNAO1 encodes Gα_o, the α subunit of G_o, a member of the G_i/o family of heterotrimeric G protein signal transducers. G_o is the most abundant membrane protein in the mammalian central nervous system and plays major roles in synaptic neurotransmission and neurodevelopment. GNAO1 mutations were first reported in early infantile epileptic encephalopathy 17 (EIEE17) but are also associated with a more common syndrome termed neurodevelopmental disorder with involuntary movements (NEDIM). Here we review a mechanistic model in which loss-of-function (LOF) GNAO1 alleles cause epilepsy and gain-of-function (GOF) alleles are primarily associated with movement disorders. We also develop a signaling framework related to cyclic AMP (cAMP), synaptic vesicle release, and neural development and discuss gene mutations perturbing those mechanisms in a range of genetic movement disorders. Finally, we analyze clinical reports of patients carrying GNAO1 mutations with respect to their symptom onset and discuss pharmacological/surgical treatments in the context of our mechanistic model.

Pediatric Palliative Care in Infants and Neonates

The application of palliative and hospice care to newborns in the neonatal intensive care unit (NICU) has been evident for over 30 years. This article addresses the history, current considerations, and anticipated future needs for palliative and hospice care in the NICU, and is based on recent literature review. Neonatologists have long managed the entirety of many newborns' short lives, given the relatively high mortality rates associated with prematurity and birth defects, but their ability or willingness to comprehensively address of the continuum of interdisciplinary palliative, end of life, and bereavement care has varied widely. While neonatology service capacity has grown worldwide during this time, so has attention to pediatric palliative care generally, and neonatal-perinatal palliative care specifically. Improvements have occurred in family-centered care, communication, pain assessment and management, and bereavement. There remains a need to integrate palliative care with intensive care rather than await its application solely at the terminal phase of a young infant's life-when s/he is imminently dying. Future considerations for applying neonatal palliative care include its integration into fetal diagnostic management, the developing era of genomic medicine, and expanding research into palliative care models and practices in the NICU.

Emerging Monogenic Complex Hyperkinetic Disorders

Purpose of Review

Hyperkinetic movement disorders can manifest alone or as part of complex phenotypes. In the era of next-generation sequencing (NGS), the list of monogenic complex movement disorders is rapidly growing. This review will explore the main features of these newly identified conditions.

Recent Findings

Mutations in ADCY5 and PDE10A have been identified as important causes of childhood-onset dyskinesias and KMT2B mutations as one of the most frequent causes of complex dystonia in children. The delineation of the phenotypic spectrum associated with mutations in ATP1A3, FOXG1, GNAO1, GRIN1, FRRS1L, and TBC1D24 is revealing an expanding genetic overlap between epileptic encephalopathies, developmental delay/intellectual disability, and hyperkinetic movement disorders,.

Summary

Thanks to NGS, the etiology of several complex hyperkinetic movement disorders has been elucidated. Importantly, NGS is changing the way clinicians diagnose these complex conditions. Shared molecular pathways, involved in early stages of brain development and normal synaptic transmission, underlie basal ganglia dysfunction, epilepsy, and other neurodevelopmental disorders.