Zika virus infection impairs synaptogenesis, induces neuroinflammation, and could be an environmental risk factor for autism spectrum disorder outcome.

Zika virus (ZIKV) infection was first associated with Central Nervous System (CNS) infections in Brazil in 2015, correlated with an increased number of newborns with microcephaly, which ended up characterizing the Congenital Zika Syndrome (CZS). Here, we investigated the impact of ZIKV infection on the functionality of iPSC-derived astrocytes. Besides, we extrapolated our findings to a Brazilian cohort of 136 CZS children and validated our results using a mouse model. Interestingly, ZIKV infection in neuroprogenitor cells compromises cell migration and causes apoptosis but does not interfere in astrocyte generation. Moreover, infected astrocytes lost their ability to uptake glutamate while expressing more glutamate transporters and secreted higher levels of IL-6. Besides, infected astrocytes secreted factors that impaired neuronal synaptogenesis. Since these biological endophenotypes were already related to Autism Spectrum Disorder (ASD), we extrapolated these results to a cohort of children, now 6-7 years old, and found seven children with ASD diagnosis (5.14 %). Additionally, mice infected by ZIKV revealed autistic-like behaviors, with a significant increase of IL-6 mRNA levels in the brain. Considering these evidence, we inferred that ZIKV infection during pregnancy might lead to synaptogenesis impairment and neuroinflammation, which could increase the risk for ASD.

Consensus from the Brazilian Academy of Neurology for the diagnosis, genetic counseling, and use of disease-modifying therapies in 5q spinal muscular atrophy.

Spinal muscular atrophy linked to chromosome 5 (SMA-5q) is an autosomal recessive genetic disease caused by mutations in the SMN1. SMA-5q is characterized by progressive degeneration of the spinal cord and bulbar motor neurons, causing severe motor and respiratory impairment with reduced survival, especially in its more severe clinical forms. In recent years, highly effective disease-modifying therapies have emerged, either acting by regulating the splicing of exon 7 of the SMN2 gene or adding a copy of the SMN1 gene through gene therapy, providing a drastic change in the natural history of the disease. In this way, developing therapeutic guides and expert consensus becomes essential to direct the use of these therapies in clinical practice. This consensus, prepared by Brazilian experts, aimed to review the main available disease-modifying therapies, critically analyze the results of clinical studies, and provide recommendations for their use in clinical practice for patients with SMA-5q. This consensus also addresses aspects related to diagnosis, genetic counseling, and follow-up of patients under drug treatment. Thus, this consensus provides valuable information regarding the current management of SMA-5q, helping therapeutic decisions in clinical practice and promoting additional gains in outcomes.

Atrofia muscular espinhal ligada ao cromossomo 5 (AME-5q) é uma doença genética de herança autossômica recessiva causada por mutações no gene SMN1. A AME-5q cursa com degeneração progressiva dos motoneurônios medulares e bulbares, acarretando grave comprometimento motor e respiratório com redução da sobrevida, especialmente nas suas formas clínicas mais graves. Nos últimos anos, terapias modificadoras da doença altamente eficazes, ou que atuam regulando o splicing do exon 7 do gene SMN2 ou adicionando uma cópia do gene SMN1 via terapia gênica, têm surgido, proporcionando uma mudança drástica na história natural da doença. Dessa forma, o desenvolvimento de guias terapêuticos e de consensos de especialistas torna-se importante no sentido de direcionar o uso dessas terapias na prática clínica. Este consenso, preparado por especialistas brasileiros, teve como objetivos revisar as principais terapias modificadoras de doença disponíveis, analisar criticamente os resultados dos estudos clínicos dessas terapias e prover recomendações para seu uso na prática clínica para pacientes com AME-5q. Aspectos relativos ao diagnóstico, aconselhamento genético e seguimento dos pacientes em uso das terapias também são abordados nesse consenso. Assim, esse consenso promove valiosas informações a respeito do manejo atual da AME-5q auxiliando decisões terapêuticas na prática clínica e promovendo ganhos adicionais nos desfechos finais.

Clinical Characterization and Underlying Genetic Findings in Brazilian Patients with Syndromic Microcephaly Associated with Neurodevelopmental Disorders.

Microcephaly is characterized by an occipitofrontal circumference at least two standard deviations below the mean for age and sex. Neurodevelopmental disorders (NDD) are commonly associated with microcephaly, due to perturbations in brain development and functioning. Given the extensive genetic heterogeneity of microcephaly, managing patients is hindered by the broad spectrum of diagnostic possibilities that exist before conducting molecular testing. We investigated the genetic basis of syndromic microcephaly accompanied by NDD in a Brazilian cohort of 45 individuals and characterized associated clinical features, as well as evaluated the effectiveness of whole-exome sequencing (WES) as a diagnostic tool for this condition. Patients previously negative for pathogenic copy number variants underwent WES, which was performed using a trio approach for isolated index cases (n = 31), only the index in isolated cases with parental consanguinity (n = 8) or affected siblings in familial cases (n = 3). Pathogenic/likely pathogenic variants were identified in 19 families (18 genes) with a diagnostic yield of approximately 45%. Nearly 86% of the individuals had global developmental delay/intellectual disability and 51% presented with behavioral disturbances. Additional frequent clinical features included facial dysmorphisms (80%), brain malformations (67%), musculoskeletal (71%) or cardiovascular (47%) defects, and short stature (54%). Our findings unraveled the underlying genetic basis of microcephaly in half of the patients, demonstrating a high diagnostic yield of WES for microcephaly and reinforcing its genetic heterogeneity. We expanded the phenotypic spectrum associated with the condition and identified a potentially novel gene (CCDC17) for congenital microcephaly.

Corrigendum to " Biochemical diagnosis of aromatic-L-amino acid decarboxylase deficiency (AADCD) by assay of AADC activity in plasma using liquid chromatography/tandem mass spectrometry" [32/100888 (2022) page 1-4].

[This corrects the article DOI: 10.1016/j.ymgmr.2022.100888.].

Biochemical diagnosis of aromatic-L-amino acid decarboxylase deficiency (AADCD) by assay of AADC activity in plasma using liquid chromatography/tandem mass spectrometry.

Aromatic l-amino acid decarboxylase (AADC, EC 4.1.1.28) deficiency is a rare genetic disorder characterized by developmental delay, oculogyric crises, autonomic dysfunction and other problems, caused by biallelic mutations in the DDC gene leading to deficient activity of aromatic l-amino acid decarboxylase, an enzyme involved in the formation of important neurotransmitters, such as dopamine and serotonin. A clinical development program of gene therapy for AADC deficiency is ongoing. An important step for the success of this therapy is the early and precise identification of the affected individuals, but it has been estimated that around 90% of the cases remain undiagnosed. The availability measurement of the AADC activity is mandatory for an accurate biochemical diagnosis. Based on these statements, our objectives were to develop a liquid chromatography tandem mass spectrometry (LC-MS/MS) method suitable for the determination of the AADC activity, and to evaluate its capacity to confirm the deficiency of AADC in potential patients in Brazil. The AADC activities were measured in plasma samples of seven AADC deficient patients and 35 healthy controls, after enzymatic reaction and LC-MS/MS analysis of dopamine, the main reaction product. The results obtained showed clear discrimination between confirmed AADC deficient patients and healthy controls. The method presented here could be incorporated in the IEM laboratories for confirmation of the diagnosis of when a suspicion of AADC deficiency is present due to clinical signs and/or abnormal biomarkers, including when an increased level of 3-O-methyldopa (3-OMD) is found in dried blood spots (DBS) samples from high-risk patients or from newborn screening programs.

Epilepsy and EEG Abnormalities in Congenital Zika Syndrome.

SUMMARY: The congenital Zika syndrome is a new entity of a group of etiologies that can lead to microcephaly and other brain damages during pregnancy, such as toxoplasmosis, rubeola, cytomegalovirus, and herpes simplex. The Zika virus crosses the placental barrier and, predominantly, affects neuronal progenitor cells. This disruptive process results in severe cortical developmental disorder, calcifications, cortical and subcortical atrophies, and malformations of the cerebellum, brain stem, and spinal cord. Children with congenital Zika syndrome have a set of clinical findings, such as cerebral palsy, dysphagia, orthopedic deformities, visual and auditory impairment, and, rarely, hydrocephalus. Because of the severity of brain lesions, epilepsy is a common finding and a frequent cause of increased morbidity. The prevalence of epilepsy in different series of patients ranges from 37.7% to 71.4%. The aim of this study is to review the studies published so far regarding epilepsy and the EEG pattern in series of patients with congenital Zika syndrome.

Corrigendum to "Evaluation of 3-O-methyldopa as a biomarker for aromatic L-amino acid decarboxylase deficiency in 7 Brazilian cases" [27/100744/2021/ pages: 1-4].

[This corrects the article DOI: 10.1016/j.ymgmr.2021.100744.].

Evaluation of 3-O-methyldopa as a biomarker for aromatic L-amino acid decarboxylase deficiency in 7 Brazilian cases.

Aromatic L-amino acid decarboxylase (AADCD) deficiency is an autosomal recessive neurometabolic disorder, caused by biallelic mutations in the DDC gene, that impairs the synthesis or metabolism of neurotransmitters leading to severe motor dysfunction. The main clinical signs are oculogyric crisis, hypotonia, hypokinesia, and dystonia. The biochemical diagnosis can be performed in cerebrospinal fluid by neurotransmitter analysis, which requires an invasive lumbar puncture, and the sample needs to be shipped frozen to a reference laboratory, usually across a country border. Measurement of AADC activity in plasma is also possible, but available in a few labs globally. 3-O-methyldopa (3-OMD) is a catabolic product of L-dopa and it is elevated in patients with AADC deficiency. The quantification of 3-OMD can be performed in dried blood spots (DBS), a sample that could be shipped at room temperature. 3-OMD levels of AADCD patients and controls were quantified in DBS by liquid chromatography tandem mass spectrometry. DBS samples from 7 Brazilian patients previously diagnosed with AADCD were used to validate the 3-OMD quantification as a screening procedure for this condition. All AADCD patients had at least a four-fold increase of 3-OMD. Thus, 3-OMD seems to be a reliable marker for AADCD, with potential use also in the newborn screening of this disease.

Genetic polymorphisms of the serotonin transporter are not related with depression in temporal lobe epilepsy caused by hippocampal sclerosis.

BACKGROUND: Mood disorders are the most frequent psychiatric disorders in patients with temporal lobe epilepsy caused by hippocampal sclerosis (TLE-HS). The pathophysiological mechanisms in common between TLE and mood disorders include abnormalities in the serotonergic pathway. We aimed to evaluate the association between serotonin transporter genetic polymorphisms - 5-HTTLPR and 5-HTTVNTR - and the presence of mood disorders in patients with TLE-HS. METHODS: We evaluated 119 patients with TLE-HS, with and without psychiatric disorder; 146 patients diagnosed with major depressive disorder (MDD), and 113 healthy volunteers. Individuals were genotyped for the 5-HTTLPR and 5-HTTVNTR polymorphisms. RESULTS: No difference was observed between the TLE-HS groups, healthy controls, and MDD without epilepsy. There was a correlation between the 12-allele of the 5-HTTVNTR and the family history of patients with epilepsy with TLE-HS (p = 0.013). CONCLUSIONS: In this study conducted in two Brazilian centers, the serotonin transporter polymorphisms evaluated cannot be associated with depressive disorder in patients with TLE-HS. Still, they do have some influence over some clinical characteristics of epilepsy in TLE-HS. These data may not be reproduced in other populations with distinct ethnic characteristics.

cGAS-mediated induction of type I interferon due to inborn errors of histone pre-mRNA processing.

Inappropriate stimulation or defective negative regulation of the type I interferon response can lead to autoinflammation. In genetically uncharacterized cases of the type I interferonopathy Aicardi-Goutières syndrome, we identified biallelic mutations in LSM11 and RNU7-1, which encode components of the replication-dependent histone pre-mRNA-processing complex. Mutations were associated with the misprocessing of canonical histone transcripts and a disturbance of linker histone stoichiometry. Additionally, we observed an altered distribution of nuclear cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) and enhanced interferon signaling mediated by the cGAS-stimulator of interferon genes (STING) pathway in patient-derived fibroblasts. Finally, we established that chromatin without linker histone stimulates cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) production in vitro more efficiently. We conclude that nuclear histones, as key constituents of chromatin, are essential in suppressing the immunogenicity of self-DNA.

Continuous epileptiform discharges during sleep as an evolutionary pattern in patients with congenital Zika virus syndrome.

Congenital Zika virus syndrome (CZVS) is associated with severe neurological deficits. Clinical characteristics of epilepsy and the electroencephalographic (EEG) pattern in CZVS were documented in infancy. In this study, we aimed to describe the EEG findings observed during the follow-up of children with CZVS. Seventy-six EEGs of 55 children (60% female; mean age = 50 months) with confirmed CZVS were analyzed, considering the background, interictal, and ictal epileptiform discharges. Continuous (or almost continuous) epileptiform discharges during non-rapid eye movement sleep were identified in 22 (40%) patients. In 20 (90.1%) patients, the pattern was symmetrical, with an anterior predominance of the epileptiform activity. All patients with this pattern had epilepsy, which was severe in 15 (68.2%) and demanded polytherapy in 19 (86.4%). Subcortical calcifications (77.3%) and multifocal EEGs (72.8%) in earlier ages occurred more often in patients with this pattern. Other unspecific interictal EEG patterns were focal epileptiform discharges in 23 (41.8%) and multifocal activity in six (10.9%). In CZVS, continuous (or almost continuous) epileptiform discharges during sleep emerge as a pattern after the second year of life. This was associated with severe and drug-resistant epilepsy, but not necessarily with an apparent regression. Subcortical calcifications and multifocal epileptiform discharges in infancy are associated with this pattern.

Movement disorders in children with congenital Zika virus syndrome.

BACKGROUND: Congenital Zika Virus Syndrome (CZVS) denotes the neurologic and developmental sequelae of congenital infection of the Zika virus. While prior studies have detailed the associated clinical phenotypes, new findings continue to be identified. Abnormal postures and movements have been previously described in children with CZVS, but not in detail. OBJECTIVE: To examine a cohort of infants with CZVS and characterize the spectrum of motor abnormalities, especially movement disorders. DESIGN: Cross-sectional prospective study of 21 infants with confirmed CZVS. SETTING: Single-center cohort of 32 patients with serologically confirmed CZVS cared for in a referral center in Brazil. PARTICIPANTS: 21 children (67% female), evaluated by two child neurologists and one movement disorders specialist, with clinical and laboratory diagnosis of CZVS aged between 16 and 30 months, with a mean age of 16 months at the time of the last examination. MAIN OUTCOME(S) AND MEASURE(S): Prospective neurologic examination by a team of three neurologists, including one movement disorders specialist. Sixteen (76.2%) children had a longitudinal evaluation with a six-month interval. The same team of experts analyzed recorded videos of all patients to characterize motor abnormalities and movement disorders. Neuroimaging findings were also analyzed to correlate with clinical findings. RESULTS: Twenty (95.2%) patients presented with dystonic postures, including "125" posture of the fingers in 17 (80.1%), "swan neck" posture of the fingers in three (18.8%), oromandibular dystonia in nine (42.9%), extensor axial hypertonia in eight (38.1%) and internal rotation of the shoulder posture in two (9.5%). Four (19%) patients had tremor. All children had malformations of cortical development, and in 13 (61.9%), the pattern was consistent with a severe and diffuse gyral simplification. Seventeen children (81%) had calcification in the transition of grey and white matter, whereas 11 (52.4%) patients had basal ganglia calcifications. CONCLUSION AND RELEVANCE: In our series, dystonic postures and other extrapyramidal signs were frequent and potentially disabling. Although children with CZVS are assessed and treated for spasticity, dystonia and other movement disorders remain neglected. This study emphasizes that extrapyramidal findings may potentially influence optimal strategies for rehabilitation and management.

Recessive congenital myasthenic syndrome caused by a homozygous mutation in SYT2 altering a highly conserved C-terminal amino acid sequence.

Defects in the gene encoding synaptotagmin 2 (SYT2) have been linked to a presynaptic congenital myasthenic syndrome (CMS) and motor neuropathies. However, to date only dominant forms of the disease have been described. We report here a consanguineous patient with a severe recessive form of presynaptic CMS and denervation atrophy caused by the homozygous mutation c.1191delG, p.Arg397Serfs*37 in SYT2. The affected 2-year-old girl had profound weakness and areflexia with moderate bulbar deficit. Repetitive nerve stimulation revealed an extreme reduction of compound muscle action potential amplitudes at rest, with a striking facilitation followed by a progressive decline at fast stimulation rates. These findings were reminiscent, but not identical to those seen in the Lambert-Eaton myasthenic syndrome. 3,4 diaminopyridine and pyridostigmine were effective to ameliorate muscle fatigue, but albuterol was ineffective. Modeling of the mutation using the rat Syt1 C2B x-ray structure revealed that Arg397Serfs*37 disrupts a highly conserved amino acid sequence at the bottom face of the C2B domain not directly involved in calcium binding, but crucial for synaptotagmin-SNARE interaction and exocytosis. Thus, this report describes a recessive form of synaptotagmin 2-CMS and highlights the importance of the synaptotagmin C-terminal on synaptic vesicle fusion and exocytosis.

Association of Severe Hydrocephalus With Congenital Zika Syndrome.

Importance: Hydrocephalus is a treatable but potentially fatal complication that has not been previously described in congenital Zika syndrome (CZS). Objective: To describe the clinical features and imaging findings in 24 patients with congenital Zika syndrome (CZS) who developed hydrocephalus. Design, Setting, and Participants: This case series included patients with hydrocephalus who were born in October and November 2015 and followed up until mid-2017 in the 2 largest national referral centers for CZS in Brazil. The participants included consecutively enrolled children with a clinical and laboratorial diagnosis of CZS who developed clinical and/or image findings suggestive of hydrocephalus and who were confirmed to experience increased intracranial hypertension during ventriculoperitoneal shunt procedures. Main Outcomes and Measures: To retrospectively describe clinical and image findings in these 24 patients. Results: This multicenter cohort included 308 patients with CZS; 24 consecutive children were enrolled in this study. These children were aged between 3 to 18 months, and 13 of 24 (54%) were female. All patients presented with at least 1 positive test result for anti-Zika antibodies in cerebrospinal fluid or serum and had classic signs of CZS. At the time of hydrocephalus diagnosis, only 14 of 24 patients (58%) had symptoms and signs suggestive of hydrocephalus (mainly worsening seizures, vomiting, irritability, and/or sudden increase of head circumference percentile). Two of 24 patients (8%) had no symptoms suggestive of hydrocephalus but were found to have reduced brain volume on repeated imaging. Cerebellar or brainstem hypoplasia on baseline imaging were found in 18 of 23 patients (78%). At the second computed tomographic scan, all patients showed a marked increase of ventricular volume, compatible with communicating hydrocephalus, and reduction of brain tissue that was visibly worse than on baseline imaging for the 23 patients with repeated scans. Conclusions and Relevance: We present evidence that hydrocephalus is a complication of CZS in at least a proportion of patients. The clinical spectrum of this condition continues to evolve, but given that presenting signs and symptoms of hydrocephalus can be challenging to recognize in CZS, we provisionally recommend that high suspicion and appropriate monitoring for hydrocephalus should be part of the standard care of patients with CZS.

Higher transcription alleles of the MAOA-uVNTR polymorphism are associated with higher seizure frequency in temporal lobe epilepsy.

BACKGROUND: There is evidence of an imbalance in the neuromodulatory system mediated by serotonin (5-HT) in patients with drug-resistant temporal lobe epilepsy (TLE). This study analyzed the monoamine oxidase A promoter variable number of tandem repeats (MAOA-uVNTR) polymorphism in patients with temporal lobe epilepsy with hippocampal sclerosis (TLE-HS). Therefore, we assessed the association between this genetic variant and seizure predisposition and severity in patients with TLE-HS. METHODS: One hundred nineteen patients with TLE-HS and 113 healthy volunteers were assessed. First, we genotyped all individuals for the MAOA-uVNTR genetic polymorphism. Second, we compared patients and controls and evaluated clinical variants of epilepsy. RESULTS: There was no difference between the TLE-HS and control groups regarding genotypic and allelic distributions of MAOA-uVNTR polymorphism (p = 1.000). Higher transcription alleles of the MAOA-uVNTR were associated with higher seizure frequency (p = 0.032) and bilateral tonic-clonic seizures (p = 0.016). CONCLUSIONS: In a selected group of patients with TLE-HS, the polymorphism MAOA-uVNTR was associated with some aspects of epilepsy severity, namely seizure frequency and bilateral tonic-clonic seizures.

Genetic polymorphisms of the 5HT receptors are not related with depression in temporal lobe epilepsy caused by hippocampal sclerosis.

BACKGROUND: Temporal lobe epilepsy caused by hippocampal sclerosis (TLE-HS) is the most frequent form of drug-resistant epilepsy in adults. Mood disorders are the most frequent psychiatric comorbidities observed in these patients. Common pathophysiological mechanisms of epilepsy and psychiatric comorbidities include abnormalities in the serotonin pathway. The primary goal of this study was to determine the possible association between polymorphisms of genes encoding the serotonin receptors 5HT1A (rs6295), 5HT1B (rs6296), and 5HT2C (rs6318) and the presence of mood disorders in patients with TLE-HS. Our secondary goal was to evaluate the possible association between these variants and susceptibility to develop seizures in TLE-HS. METHODS: We assessed 119 patients with TLE-HS, with and without psychiatric comorbidities; 146 patients with major depressive disorder; and 113 healthy volunteers. Individuals were genotyped for the rs6295, rs6296, and rs6318 polymorphisms. RESULTS: No difference was observed between the group with TLE-HS, healthy controls, and the group with major depressive disorder without epilepsy regarding the polymorphisms that were evaluated. There was no correlation between rs6318, rs6295, rs6296, and epilepsy-related factors and history of psychiatric comorbidities. CONCLUSIONS: Our work suggests that the studied polymorphisms were not related to the presence of TLE, psychiatric comorbidities in TLE, and epilepsy-related factors.

Publisher Correction: Discordant congenital Zika syndrome twins show differential in vitro viral susceptibility of neural progenitor cells.

The original PDF version of this Article contained errors in the spelling of Luiz Carlos Caires-Júnior, Uirá Souto Melo, Bruno Henrique Silva Araujo, Alessandra Soares-Schanoski, Murilo Sena Amaral, Kayque Alves Telles-Silva, Vanessa van der Linden, Helio van der Linden, João Ricardo Mendes de Oliveira, Nivia Maria Rodrigues Arrais, Joanna Goes Castro Meira, Ana Jovina Barreto Bispo, Esper Abrão Cavalheiro, and Robert Andreata-Santos, which were incorrectly given as Luiz Carlos de Caires Jr., UiráSouto Melo, Bruno Silva Henrique Araujo, Alessandra Soares Schanoski, MuriloSena Amaral, Kayque Telles Alves Silva, Vanessa Van der Linden, Helio Van der Linden, João Mendes Ricardo de Oliveira, Nivia Rodrigues Maria Arrais, Joanna Castro Goes Meira, Ana JovinaBarreto Bispo, EsperAbrão Cavalheiro, and Robert Andreata Santos. Furthermore, in both the PDF and HTML versions of the Article, the top panel of Fig. 3e was incorrectly labeled '10608-1' and should have been '10608-4', and financial support from CAPES and DECIT-MS was inadvertently omitted from the Acknowledgements section. These errors have now been corrected in both the PDF and HTML versions of the Article.

Discordant congenital Zika syndrome twins show differential in vitro viral susceptibility of neural progenitor cells.

Congenital Zika syndrome (CZS) causes early brain development impairment by affecting neural progenitor cells (NPCs). Here, we analyze NPCs from three pairs of dizygotic twins discordant for CZS. We compare by RNA-Seq the NPCs derived from CZS-affected and CZS-unaffected twins. Prior to Zika virus (ZIKV) infection the NPCs from CZS babies show a significantly different gene expression signature of mTOR and Wnt pathway regulators, key to a neurodevelopmental program. Following ZIKV in vitro infection, cells from affected individuals have significantly higher ZIKV replication and reduced cell growth. Whole-exome analysis in 18 affected CZS babies as compared to 5 unaffected twins and 609 controls excludes a monogenic model to explain resistance or increased susceptibility to CZS development. Overall, our results indicate that CZS is not a stochastic event and depends on NPC intrinsic susceptibility, possibly related to oligogenic and/or epigenetic mechanisms.

Discordant congenital Zika syndrome twins show differential in vitro viral susceptibility of neural progenitor cells

Congenital Zika syndrome (CZS) causes early brain development impairment by affecting neural progenitor cells (NPCs). Here, we analyze NPCs from three pairs of dizygotic twins discordant for CZS. We compare by RNA-Seq the NPCs derived from CZS-affected and CZS-unaffected twins. Prior to Zika virus (ZIKV) infection the NPCs from CZS babies show a significantly different gene expression signature of mTOR and Wnt pathway regulators, key to a neurodevelopmental program. Following ZIKV in vitro infection, cells from affected individuals have significantly higher ZIKV replication and reduced cell growth. Whole-exome analysis in 18 affected CZS babies as compared to 5 unaffected twins and 609 controls excludes a monogenic model to explain resistance or increased susceptibility to CZS development. Overall, our results indicate that CZS is not a stochastic event and depends on NPC intrinsic susceptibility, possibly related to oligogenic and/or epigenetic mechanisms.