Phenotypic Spectrum ofCOL4A1Mutations: Porencephaly to Schizencephaly

Evaluating neural crest cell migration in a Col4a1 mutant mouse model of ocular anterior segment dysgenesis

The periocular mesenchyme (POM) is a transient migratory embryonic tissue derived from neural crest cells (NCCs) and paraxial mesoderm that gives rise to most of the structures in front of the eye. Morphogenetic defects of these structures can impair aqueous humor outflow, leading to elevated intraocular pressure and glaucoma. Mutations in collagen type IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause Gould syndrome - a multisystem disorder often characterized by variable cerebrovascular, ocular, renal, and neuromuscular manifestations. Approximately one-third of individuals with COL4A1 and COL4A2 mutations have ocular anterior segment dysgenesis (ASD), including congenital glaucoma resulting from abnormalities of POM-derived structures. POM differentiation has been a major focus of ASD research, but the underlying cellular mechanisms are still unclear. Moreover, earlier events including NCC migration and survival defects have been implicated in ASD; however, their roles are not as well understood. Vascular defects are among the most common consequences of COL4A1 and COL4A2 mutations and can influence NCC survival and migration. We therefore hypothesized that NCC migration might be impaired by COL4A1 and COL4A2 mutations. In this study, we used 3D confocal microscopy, gross morphology, and quantitative analyses to test NCC migration in Col4a1 mutant mice. We show that homozygous Col4a1 mutant embryos have severe embryonic growth retardation and lethality, and we identified a potential maternal effect on embryo development. Cerebrovascular defects in heterozygous Col4a1 mutant embryos were present as early as E9.0, showing abnormal cerebral vasculature plexus remodeling compared to controls. We detected abnormal NCC migration within the diencephalic stream and the POM in heterozygous Col4a1 mutants whereby mutant NCCs formed smaller diencephalic migratory streams and POMs. In these settings, migratory NCCs within the diencephalic stream and POM localize farther away from the developing vasculature. Our results show for the first time that Col4a1 mutations lead to cranial NCCs migratory defects in the context of early onset defective angiogenesis without affecting cell numbers, possibly impacting the relation between NCCs and the blood vessels during ASD development.

Comprehensive whole-genome sequence analyses provide insights into the genomic architecture of cerebral palsy

We performed whole-genome sequencing (WGS) in 327 children with cerebral palsy (CP) and their biological parents. We classified 37 of 327 (11.3%) children as having pathogenic/likely pathogenic (P/LP) variants and 58 of 327 (17.7%) as having variants of uncertain significance. Multiple classes of P/LP variants included single-nucleotide variants (SNVs)/indels (6.7%), copy number variations (3.4%) and mitochondrial mutations (1.5%). The COL4A1 gene had the most P/LP SNVs. We also analyzed two pediatric control cohorts (n = 203 trios and n = 89 sib-pair families) to provide a baseline for de novo mutation rates and genetic burden analyses, the latter of which demonstrated associations between de novo deleterious variants and genes related to the nervous system. An enrichment analysis revealed previously undescribed plausible candidate CP genes (SMOC1, KDM5B, BCL11A and CYP51A1). A multifactorial CP risk profile and substantial presence of P/LP variants combine to support WGS in the diagnostic work-up across all CP and related phenotypes.

Diagnostic utility of exome sequencing followed by research reanalysis in human brain malformations

This study aimed to determine the diagnostic yield of singleton exome sequencing and subsequent research-based trio exome analysis in children with a spectrum of brain malformations seen commonly in clinical practice. We recruited children ≤ 18 years old with a brain malformation diagnosed by magnetic resonance imaging and consistent with an established list of known genetic causes. Patients were ascertained nationally from eight tertiary paediatric centres as part of the Australian Genomics Brain Malformation Flagship. Chromosome microarray was required for all children, and those with pathogenic copy number changes were excluded. Cytomegalovirus polymerase chain reaction on neonatal blood spots was performed on all children with polymicrogyria with positive patients excluded. Singleton exome sequencing was performed through a diagnostic laboratory and analysed using a clinical exome sequencing pipeline. Undiagnosed patients were followed up in a research setting, including reanalysis of the singleton exome data and subsequent trio exome sequencing. A total of 102 children were recruited. Ten malformation subtypes were identified with the commonest being polymicrogyria (36%), pontocerebellar hypoplasia (14%), periventricular nodular heterotopia (11%), tubulinopathy (10%), lissencephaly (10%) and cortical dysplasia (9%). The overall diagnostic yield for the clinical singleton exome sequencing was 36%, which increased to 43% after research follow-up. The main source of increased diagnostic yield was the reanalysis of the singleton exome data to include newly discovered gene-disease associations. One additional diagnosis was made by trio exome sequencing. The highest phenotype-based diagnostic yields were for cobblestone malformation, tubulinopathy and lissencephaly and the lowest for cortical dysplasia and polymicrogyria. Pathogenic variants were identified in 32 genes, with variants in 6/32 genes occurring in more than one patient. The most frequent genetic diagnosis was pathogenic variants in TUBA1A. This study shows that over 40% of patients with common brain malformations have a genetic aetiology identified by exome sequencing. Periodic reanalysis of exome data to include newly identified genes was of greater value in increasing diagnostic yield than the expansion to trio exome. This study highlights the genetic and phenotypic heterogeneity of brain malformations, the importance of a multidisciplinary approach to diagnosis and the large number of patients that remain without a genetic diagnosis despite clinical exome sequencing and research reanalysis.

Clinical and neuroimaging review of monogenic cerebral small vessel disease from the prenatal to adolescent developmental stage

Cerebral small vessel disease (cSVD) refers to a group of pathological processes with various etiologies affecting the small vessels of the brain. Most cases are sporadic, with age-related and hypertension-related sSVD and cerebral amyloid angiopathy being the most prevalent forms. Monogenic cSVD accounts for up to 5% of causes of stroke. Several causative genes have been identified. Sporadic cSVD has been widely studied whereas monogenic cSVD is still poorly characterized and understood. The majority of cases of both the sporadic and monogenic types, including cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), typically have their onset in adulthood. Types of cSVD with infantile and childhood onset are rare, and their diagnosis is often challenging. The present review discusses the clinical and neuroimaging findings of monogenic cSVD from the prenatal to adolescent period of development. Early diagnosis is crucial to enabling timely interventions and family counseling.

Good Outcome of Resective Epilepsy Surgery in a 1-Year-Old Child with Drug-Resistant Focal Epilepsy with a Novel Pathogenic COL4A1 Mutation

Pathogenic variants in COL4A1, encoding the α chain of type IV collagen, have been associated with cerebrovascular pathology as well as malformations of cortical development, thereby causing structural epilepsy. This case illustrates successful resective epilepsy surgery in a 12-month-old girl with left occipital focal cortical dysplasia (FCD) associated with a heterozygous splice-donor variant in COL4A1. She presented with drug-resistant focal epilepsy with daily seizures from the age of 2 months, refractory to several combinations of antiseizure medications, as well as mild right-sided hemiparesis and developmental delay. All presurgical diagnostic modalities, including ictal and interictal electroencephalography, magnetic resonance imaging, and ictal fluorodeoxyglucose positron emission tomography, showed congruent findings, pointing toward one single left occipital epileptogenic zone (EZ). We performed a left occipital lobectomy, using intraoperative electrocorticography to confirm the boundaries of the EZ. After surgery, the patient has remained seizure free, and both cognitive and motor developments have improved. Histopathology of the resected brain tissue showed FCD type Ia. Resective epilepsy surgery can have a very good outcome, also in patients with genetic mutations in COL4A1, constituting a less invasive option than the previously used more radical surgical procedures such as hemispherectomy.

Schizencephaly diagnosed after an episode of seizure during labor: A case report

Schizencephaly, an extremely rare anomaly of the cortex, is characterized by abnormal clefts in the cerebral cortex. Very often, this condition is diagnosed early in the childhood period but few instances exist in literature where schizencephaly-associated seizures and hemiparesis have presented later in life too. Here, we report a rare case scenario of a lady in her late 30s who initially presented to us with obstetric concerns wherein schizencephaly remained an incidental finding despite the significantly large cortical cleft along with lobar holoprosencephaly and lissencephaly.

High Prevalence of Collagenopathies in Preterm- and Term-Born Children With Periventricular Venous Hemorrhagic Infarction

INTRODUCTION

The aim of this study was to evaluate genetic risk factors in term-born children with antenatal periventricular hemorrhagic infarction (PVHI), presumed antenatal periventricular venous infarction and periventricular hemorrhagic infarction in preterm neonates.

METHODS

Genetic analysis and magnetic resonance imaging were performed in 85 children: term-born children (≥36 gestational weeks) with antenatal periventricular hemorrhagic infarction (n = 6) or presumed antenatal (n = 40) periventricular venous infarction and preterm children (<36 gestational weeks) with periventricular hemorrhagic infarction (n = 39). Genetic testing was performed using exome or large gene panel (n = 6700 genes) sequencing.

RESULTS

Pathogenic variants associated with stroke were found in 11 of 85 (12.9%) children with periventricular hemorrhagic infarction/periventricular venous infarction. Among the pathogenic variants, COL4A1/A2 and COL5A1 variants were found in 7 of 11 (63%) children. Additionally, 2 children had pathogenic variants associated with coagulopathy, whereas 2 other children had other variants associated with stroke. Children with collagenopathies had significantly more often bilateral multifocal stroke with severe white matter loss and diffuse hyperintensities in the white matter, moderate to severe hydrocephalus, moderate to severe decrease in size of the ipsilesional basal ganglia and thalamus compared to children with periventricular hemorrhagic infarction/periventricular venous infarction without genetic changes in the studied genes (P ≤ .01). Severe motor deficit and epilepsy developed more often in children with collagenopathies compared to children without genetic variants (P = .0013, odds ratio [OR] = 233, 95% confidence interval [CI]: 2.8-531; and P = .025, OR = 7.3, 95% CI: 1.3-41, respectively).

CONCLUSIONS

Children with periventricular hemorrhagic infarction/periventricular venous infarction have high prevalence of pathogenic variants in collagene genes (COL4A1/A2 and COL5A1). Genetic testing should be considered for all children with periventricular hemorrhagic infarction/periventricular venous infarction; COL4A1/A2 and COL5A1/A2 genes should be investigated first.

Bi-allelic variants in the ESAM tight-junction gene cause a neurodevelopmental disorder associated with fetal intracranial hemorrhage

The blood-brain barrier (BBB) is an essential gatekeeper for the central nervous system and incidence of neurodevelopmental disorders (NDDs) is higher in infants with a history of intracerebral hemorrhage (ICH). We discovered a rare disease trait in thirteen individuals, including four fetuses, from eight unrelated families associated with homozygous loss-of-function variant alleles of ESAM which encodes an endothelial cell adhesion molecule. The c.115del (p.Arg39Glyfs∗33) variant, identified in six individuals from four independent families of Southeastern Anatolia, severely impaired the in vitro tubulogenic process of endothelial colony-forming cells, recapitulating previous evidence in null mice, and caused lack of ESAM expression in the capillary endothelial cells of damaged brain. Affected individuals with bi-allelic ESAM variants showed profound global developmental delay/unspecified intellectual disability, epilepsy, absent or severely delayed speech, varying degrees of spasticity, ventriculomegaly, and ICH/cerebral calcifications, the latter being also observed in the fetuses. Phenotypic traits observed in individuals with bi-allelic ESAM variants overlap very closely with other known conditions characterized by endothelial dysfunction due to mutation of genes encoding tight junction molecules. Our findings emphasize the role of brain endothelial dysfunction in NDDs and contribute to the expansion of an emerging group of diseases that we propose to rename as "tightjunctionopathies."

Elevated TGFβ signaling contributes to cerebral small vessel disease in mouse models of Gould syndrome

Cerebral small vessel disease (CSVD) is a leading cause of stroke and vascular cognitive impairment and dementia. Studying monogenic CSVD can reveal pathways that are dysregulated in common sporadic forms of the disease and may represent therapeutic targets. Mutations in collagen type IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause highly penetrant CSVD as part of a multisystem disorder referred to as Gould syndrome. COL4A1 and COL4A2 form heterotrimers [a1α1α2(IV)] that are fundamental constituents of basement membranes. However, their functions are poorly understood and the mechanism(s) by which COL4A1 and COL4A2 mutations cause CSVD are unknown. We used histological, molecular, genetic, pharmacological, and in vivo imaging approaches to characterize central nervous system (CNS) vascular pathologies in Col4a1 mutant mouse models of monogenic CSVD to provide insight into underlying pathogenic mechanisms. We describe developmental CNS angiogenesis abnormalities characterized by impaired retinal vascular outgrowth and patterning, increased numbers of mural cells with abnormal morphologies, altered contractile protein expression in vascular smooth muscle cells (VSMCs) and age-related loss of arteriolar VSMCs in Col4a1 mutant mice. Importantly, we identified elevated TGFβ signaling as a pathogenic consequence of Col4a1 mutations and show that genetically suppressing TGFβ signaling ameliorated CNS vascular pathologies, including partial rescue of retinal vascular patterning defects, prevention of VSMC loss, and significant reduction of intracerebral hemorrhages in Col4a1 mutant mice aged up to 8 months. This study identifies a novel biological role for collagen α1α1α2(IV) as a regulator of TGFβ signaling and demonstrates that elevated TGFβ signaling contributes to CNS vascular pathologies caused by Col4a1 mutations. Our findings suggest that pharmacologically suppressing TGFβ signaling could reduce the severity of CSVD, and potentially other manifestations associated with Gould syndrome and have important translational implications that could extend to idiopathic forms of CSVD.

Rare metabolic disease mimicking COL4A1/COL4A2 fetal brain phenotype

Pathogenic variants of collagen type IV alpha 1 and 2 (COL4A1/COL4A2) genes cause various phenotypic anomalies, including intracerebral hemorrhage and a wide spectrum of developmental anomalies. Only 20% of fetuses referred for COL4A1/COL4A2 molecular screening (fetuses with a suspected intracerebral hemorrhage) carry a pathogenic variant in these genes, raising questions regarding the causative anomaly in the remaining 80% of these fetuses. We examined, following termination of pregnancy or in-utero fetal death, a series of 113 unrelated fetuses referred for COL4A1/COL4A2 molecular screening, in which targeted sequencing was negative. Using exome sequencing data and a gene-based collapsing test, we searched for enrichment of rare qualifying variants in our fetal cohort in comparison to the Genome Aggregation Database (gnomAD) control cohort (n = 71 702). Qualifying variants in pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) were overrepresented in our cohort, reaching genome-wide significance (P = 2.11 × 10-7 ). Heterozygous PDHA1 loss-of-function variants were identified in three female fetuses. Among these three cases, we observed microcephaly, ventriculomegaly, germinolytic pseudocysts, agenesis/dysgenesis of the corpus callosum and white-matter anomalies that initially suggested cerebral hypoxic-ischemic and hemorrhagic lesions. However, a careful a-posteriori reanalysis of imaging and postmortem data showed that the observed lesions were also consistent with those observed in fetuses carrying PDHA1 pathogenic variants, strongly suggesting that these two phenotypes may overlap. Exome sequencing should therefore be performed in fetuses referred for COL4A1/COL4A2 molecular screening which are screen-negative, with particular attention paid to the PDHA1 gene. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Ultrasound and magnetic resonance imaging features of fetal intracranial cystic lesions: A pictorial essay

This pictorial essay focuses on ultrasound (US) and magnetic resonance imaging (MRI) features of fetal intracranial cysts. Intracranial cysts are common findings in prenatal imaging, and if great attention is paid to their size, location, and imaging features, they can be diagnosed accurately. They are usually detected by fetal ultrasound exams. However, when ultrasound data on cystic lesion characteristics is insufficient, MRI and fetal neurosonogram are the best options for detecting other associated anomalies. The prognosis is highly dependent on their location and whether they are associated with other fetal anomalies.

The NESHIE and CP Genetics Resource (NCGR): A database of genes and variants reported in neonatal encephalopathy with suspected hypoxic ischemic encephalopathy (NESHIE) and consequential cerebral palsy (CP)

Neonatal encephalopathy (NE) with suspected hypoxic ischaemic encephalopathy (HIE) (NESHIE) is a complex syndrome occurring in newborns, characterised by altered neurological function. It has been suggested that genetic variants may influence NESHIE susceptibility and outcomes. Unlike NESHIE, for which a limited number of genetic studies have been performed, many studies have identified genetic variants associated with cerebral palsy (CP), which can develop from severe NESHIE. Identifying variants in patients with CP, as a consequence of NESHIE, may provide a starting point for the identification of genetic variants associated with NESHIE outcomes. We have constructed NCGR (NESHIE and CP Genetics Resource), a database of genes and variants reported in patients with NESHIE and CP (where relevant to NESHIE), for the purpose of collating and comparing genetic findings between the two conditions. In this paper we describe the construction and functionality of NCGR. Furthermore, we demonstrate how NCGR can be used to prioritise genes and variants of potential clinical relevance that may underlie a genetic predisposition to NESHIE and contribute to an understanding of its pathogenesis.

Delineating septo-optic dysplasia

BACKGROUND

Septo-optic dysplasia (SOD), once a variable triad of septum pellucidum defects (SPDs), optic nerve hypoplasia (ONH), and hypopituitarism, has had multiple findings added, with uncertain causes, definitions, and limits.

METHOD

Literature review.

RESULTS

SOD is a complex vascular sequence with confounders.

CONCLUSIONS

Proximal anterior cerebral artery trunk disruptions cause overlapping primary effects, giving ONH alone most often, and isolated SPD less. ONH disruptions can spread to pituitary, SPD disruptions to the cerebral cortex, causing schizencephaly and related anomalies. Pituitary defects are rare without ONH, and cortical findings are rare without SPD. Extensions are unidirectional, so isolated pituitary or cortical defects are separate from SOD. Micro- an- ophthalmia, a suggested ONH variant, is not part of SOD. Disruption by-products can affect development, causing cognitive and endocrine issues, and structural anomalies such as corpus callosum thinning, ventriculomegaly, and hippocampal and olfactory findings. Limbic extensions may also contribute to the same structural defects as by-products. Midline CNS developmental anomalies can act as disruptive foci, most likely through vascular variants, but have separate pathogenesis. Relative frequencies of specific pituitary hormone defects change as SOD rates increase. Increasing relative rates of midline CNS developmental defects and cortical anomalies are consistent with rising levels of exogenous exposures sensitizing to midline predispositions.

Hypothesis: By-products of vascular disruption carried in the CSF affect prenatal brain development

Prenatal CNS disruptions can be associated with physically separate findings. Examples include cognitive issues in septo-optic dysplasia and sporadic and WNT1-related unilateral cerebellar hypoplasia, and physical findings such as thinning of the corpus callosum, ventriculomegaly, hippocampal abnormalities, olfactory tract and bulb hypoplasia, and distant cortical dysplasias with schizencephaly. Similar effects to toxicities with intraventricular hemorrhage in prematurity could occur earlier in development. CSF transportation of disruption by-products would provide access to vulnerable areas through inflammatory effects on blood-brain barrier permeability. Outcomes are influenced by location and volume of byproducts in the CSF, timing, transport, and inflammatory responses. A particular association of vermis disruption with cognitive issues may be related to CSF flow distortions that avoid toxin dilutions in the third ventricle. Symmetrical contralateral cortical dysplasia with schizencephaly may reflect immunovascular field-related vulnerabilities seen in situations such as vitiligo.

Prenatal Diagnosis of COL4A1 Mutations in Eight Cases: Further Delineation of the Neurohistopathological Phenotype

BACKGROUND

Increasing number of mutations responsible for vascular lesions, leading to ischemic or hemorrhagic stroke in young adults, has been identified in the recent years. It has been demonstrated in both mice and humans, that mutations in COL4A1 gene promote cerebral hemorrhages. In humans, both adults and children may be affected, and the spectrum has been broadened recently to neonates and fetuses.

METHODS

We present a cohort of eight COL4A1 mutated fetuses in which cerebral hemorrhages were detected by ultrasound leading to elective terminations of pregnancy.

RESULTS

Our neuropathological studies demonstrated a strikingly similar pathological pattern, dominated by supra- and infratentorial multifocal hemorrhagic lesions of various abundance and age in the vicinity of enlarged small vessels having a discontinuous wall. This was constantly associated with a spectrum of supratentorial post-ischemic damages of the grey and white matters. Morphometric studies of brain vessels confirmed vascular dilation and hypervascularization in both grey and white matters and severe attenuation of the smooth-muscle actin staining in the white matter.

CONCLUSION

These observations add to the rare human neuropathological phenotype of COL4A1 mutations. Its recognition is mandatory to enhance the number of tested patients in the future, as well as the genetic counseling of parents.

Congenital Brain Malformations: An Integrated Diagnostic Approach

Congenital brain malformations are abnormalities present at birth that can result from developmental disruptions at various embryonic or fetal stages. The clinical presentation is nonspecific and can include developmental delay, hypotonia, and/or epilepsy. An informed combination of imaging and genetic testing enables early and accurate diagnosis and management planning. In this article, we provide a streamlined approach to radiologic phenotyping and genetic evaluation of brain malformations. We will review the clinical workflow for brain imaging and genetic testing with up-to-date ontologies and literature references. The organization of this article introduces a streamlined approach for imaging-based etiologic classification into malformative, destructive, and migrational abnormalities. Specific radiologic ontologies are then discussed in detail, with correlation of key neuroimaging features to embryology and molecular pathogenesis.

Epilepsy and related challenges in children with COL4A1 and COL4A2 mutations: A Gould syndrome patient registry

Recently, patient advocacy groups started using the name Gould syndrome to describe clinical features of COL4A1 and COL4A2 mutations. Gould syndrome is increasingly identified in genetic screening panels, and because it is a rare disease, there is a disproportionate burden on families to understand the disease and chart the course for clinical care. Among the chief concerns for caregivers of children with Gould syndrome are the challenges faced because of epilepsy, including severe manifestations such as infantile spasms. To document the concerns of the patient population, the Gould Syndrome Foundation established the Gould Syndrome Global Registry (GSGR).

METHODS

The Gould Syndrome Foundation developed questions for the GSGR with iterative input from patients and caregivers. An institutional review board issued an exemption determination before data collection began. Participants were recruited through social media and clinician referrals. All participants consented electronically, and the data were collected and managed using REDCap electronic data capture tools. De-identified data representing responses received between October 2019 and February 2021 were exported and analyzed with IBM SPSS 27 using descriptive statistics (mean, standard deviation, frequency, range, and percent).

RESULTS

Seventy families from twelve countries provided data for the registry, representing 100 affected people (40 adults and 60 children). This analysis represents a subanalysis of the 35 out of 60 children <=18 years of age who reported a history of seizures. Nearly half of these participants were diagnosed with infantile spasms. Participants with epilepsy frequently reported developmental delays (88.6%), stroke (60.0%), cerebral palsy (65.7%), and constipation (57.1%). Ten (28.6%) children use a feeding tube. Despite the fact that more than half of respondents reported stroke, only 34.3% reported ever receiving education on stroke recognition.

CONCLUSION

Here we describe the development and deployment of the first global registry for individuals and family members with Gould syndrome, caused by mutations in COL4A1 and COL4A2. It is important for pediatric neurologists to have access to resources to provide families upon diagnosis. Specifically, all families with Gould Syndrome must have access to infantile spasms awareness and stroke education materials. The Gould Syndrome Foundation is planning several improvements to this patient registry which will encourage collaboration and innovation for the benefit of people living with Gould syndrome.

Progressive cerebral atrophies in three children with COL4A1 mutations

BACKGROUND

The collagen type IV alpha 1 chain (COL4A1) gene on 13q34 encodes one chain of collagen. COL4A1 mutations have been identified as the cause of a group of multisystemic conditions in humans, including the brain, eyes, kidneys, muscles, and other organs at any age. Brain imaging shows a wide spectrum of abnormalities, including porencephaly, schizencephaly, polymicrogyria focal cortical dysplasia, periventricular leukoencephalopathy, ventricular dysmorphisms, and multiple brain calcifications. However, there are no reports in the literature showing progressive radiological findings in consecutive follow-up scans. Herein, we report three cases of COL4A1 mutations with porencephaly from gestation to five years of age or longer, and describe their clinical and brain imaging findings.

CASE REPORTS

We retrospectively reviewed the clinical symptoms and radiological findings, including brain magnetic resonance imaging (MRI) and computed tomography (CT), in three female patients with COL4A1 mutations. Their mutations were c.4843G>A (p.Glu1615Lys), c.1835G>A (p.Gly612Asp), and c.3556+1G>T respectively. All the three cases represented porencephaly in the fetal period; severe hemolytic anemia in the neonatal period; and drug-resistant epilepsy, global developmental delay, and spastic quadriplegia in their childhood.

RESULTS

Brain MRI and CT showed progressive white matter atrophy from gestation to five-year follow-up or later. Minor cerebral hemorrhage without symptoms occasionally occurred in one patient. Despite brain changes, the clinical picture was stable during early childhood.

CONCLUSIONS

COL4A1 mutations may cause progressive cerebral atrophy beyond early childhood.

A practical approach to prenatal diagnosis of malformations of cortical development

Malformations of cortical development (MCD) can frequently be diagnosed at multi-disciplinary Fetal Neurology clinics with the aid of multiplanar neurosonography and MRI. The patients are usually referred following prenatal sonographic screening that raises the suspicion of a possible underlying MCD. These indirect findings include, but are not limited to, ventriculomegaly (lateral ventricles larger than 10 mm), asymmetric ventricles, commissural anomalies, absent cavum septum pellucidum, cerebellar vermian and/or hemispheric anomalies, abnormal head circumference (microcephaly or macrocephaly), multiple CNS malformations, and associated systemic defects. The aim of this paper is to suggest a practical approach to prenatal diagnosis of malformations of cortical development utilizing dedicated neurosonography and MRI, based on the current literature and our own experience. We suggest that an MCD should be suspected in utero when the following intracranial imaging signs are present: abnormal development of the Sylvian fissure; delayed achievement of cortical milestones, premature appearance of sulcation; irregular ventricular borders, abnormal cortical thickness (thick, thin); abnormal shape and orientation of the sulci and gyri; irregular, abnormal, asymmetric, and enlarged hemisphere; simplified cortex; non continuous cortex or cleft; and intraparenchymal echogenic nodules. Following the putative diagnosis of fetal MCD by neurosonography and MRI, when appropriate and possible (depending on gestational age), the imaging diagnosis is supplemented by genetic studies (CMA and trio whole exome sequencing). In some instances, no further studies are required during pregnancy due to the clear dire prognosis and then the genetic evaluation can be deferred after delivery or termination of pregnancy (in countries where allowed).

The role of basement membranes in cardiac biology and disease

Basement membranes are highly specialised extracellular matrix structures that within the heart underlie endothelial cells and surround cardiomyocytes and vascular smooth muscle cells. They generate a dynamic and structurally supportive environment throughout cardiac development and maturation by providing physical anchorage to the underlying interstitium, structural support to the tissue, and by influencing cell behaviour and signalling. While this provides a strong link between basement membrane dysfunction and cardiac disease, the role of the basement membrane in cardiac biology remains under-researched and our understanding regarding the mechanistic interplay between basement membrane defects and their morphological and functional consequences remain important knowledge-gaps. In this review we bring together emerging understanding of basement membrane defects within the heart including in common cardiovascular pathologies such as contractile dysfunction and highlight some key questions that are now ready to be addressed.

Congenital Visual Field Loss from a Schizencephalic Cleft Damaging Meyer's Loop

A healthy, asymptomatic woman was referred after incidental discovery of a right superior incongruous hemianopia. Magnetic resonance imaging disclosed a schizencephalic cleft passing through Meyer's loop of the left optic radiation. The lesion may have resulted from a focal vascular accident or disruption of cortical neurogenesis during gestation.

Are COL4A1 and COL4A2 gene polymorphisms associated with cerebral palsy?

Objectives

This study aims to investigate the association of COL4A1 and COL4A2 gene polymorphisms with susceptibility to risk of developing cerebral palsy (CP) and severity of CP.

Patients and methods

Between December 2016 and June 2017, a total of 176 patients with CP (101 males, 75 females; mean age 71.8±37.9 months; range, 24 to 184 months) and age-, sex-, and ethnically-matched 178 (90 males, 88 females; mean age 69.3±55.2 months; range, 24 to 214 months) controls were included. Two polymorphisms of COL4A1 (rs1961495) and COL4A2 (rs9521733) genes were typed from genomic deoxyribonucleic acid. Genotype distributions and allelic frequencies were compared between the patient and control groups. Gross Motor Function Classification System, the use of medical drugs, type of involvement, number of affected limbs, accompanying conditions, birth weight, gestational age, and magnetic resonance imaging (MRI) findings were used to evaluate the disease severity and their relationships with the COL4A1 and COL4A2 gene polymorphisms.

Results

There was no statistically significant difference between the groups in terms of genotype distribution and allele frequency of COL4A1 and COL4A2 gene polymorphisms (p>0.05). In addition, there was no relationship between severity of CP and two gene polymorphisms (p>0.05). A significant association was detected between the COL4A2 polymorphism and growth retardation in CP. The TT genotype (57.1%) and T allele (76.2%) were higher, compared to CC (4.8%) and CT genotypes (38.1%) and C allele (23.8%) in patients with CP with growth retardation (p=0.03 for genotype and p=0.01 for allele frequency).

Conclusion

These findings suggest that COL4A1 and COL4A2 gene polymorphisms are not associated with susceptibility to CP in a group of Turkish populations, although COL4A2 gene polymorphism may be associated with growth retardation in patients with CP.

Brain MRI in Monogenic Cerebral Small Vessel Diseases: A Practical Handbook

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Monogenic cerebral small vessel diseases are a topic of growing interest, as several genes responsible have been recently described and new sequencing techniques such as Next generation sequencing are available. Brain imaging is a key exam in these diseases. First, since it is often the first exam performed, an MRI is key in selecting patients for genetic testing and for interpreting Next generation sequencing reports. In addition, neuroimaging can be helpful in describing the underlying pathological mechanisms involved in cerebral small vessel disease. With this review, we aim to provide Neurologists and Stroke physicians with an up-to date overview of the current neuroimaging knowledge on monogenic small vessel diseases.

Hypoxia: A teratogen underlying a range of congenital disruptions, dysplasias, and malformations

In this review, we explore evidence that hypoxia in the developing human fetus can lead not only to the more commonly accepted disruptive-type defects, but also patterns of anomalies that suggest that hypoxia can exert a more classic teratogenic effect, using the brain as one example. We review neuropathology in the context of intrauterine hypoxia, particularly as it relates to carbon monoxide poisoning, in utero strokes, and homozygous alpha-thalassemia. In general, the associated brain injuries resemble those seen with other causes of hypoxic-ischemic injury. Fetal strokes during development usually lead to loss of brain tissue in areas that do not follow a typical embryologic pattern, and therefore are considered disruptions. However, there is also evidence that fetal brain ischemia can cause more classically recognized patterns of abnormal embryonic neuronal migration and organization such as polymicrogyria, cortical dysplasia, or dysgenesis, including select types of focal cortical dysplasia. This study summarizes available literature and evidence to raise clinicians' awareness regarding the association between hypoxia and congenital anomalies, including brain malformations.

Prevalence of COL4A1 and COL4A2 mutations in severe fetal multifocal hemorrhagic and/or ischemic cerebral lesions

OBJECTIVE

To establish the prevalence of COL4A1 and COL4A2 gene mutations in fetuses presenting with a phenotype suggestive of cerebral injury.

METHODS

This was a single-center retrospective analysis of all cases of fetal cerebral anomalies suggestive of COL4A1 or COL4A2 gene mutation over the period 2009-2018. Inclusion criteria were: (1) severe and/or multifocal hemorrhagic cerebral lesions; (2) multifocal ischemic-hemorrhagic cerebral lesions. These anomalies could be of different ages and associated with schizencephaly or porencephaly. Between fetuses with and those without a mutation, we compared gestational age at the time of diagnosis, parity and fetal gender.

RESULTS

Among the 956 cases of cerebral anomaly diagnosed in our center during the 10-year study period, 18 fetuses were identified for inclusion. A pathogenic COL4A1 gene mutation was found in five of these cases, among which four were de-novo mutations. A variant of unknown significance was found in four fetuses: in the COL4A1 gene in one case and in the COL4A2 gene in three cases. No COL4A1 or COL4A2 mutation was found in the remaining nine fetuses. The median (interquartile range) gestational age at diagnosis was significantly lower in cases with a mutation (24 (22-26) weeks) than in cases without a mutation (32 (29.5-34.5) weeks) (P = 0.03).

CONCLUSIONS

A phenotype suggestive of cerebral injury was found in 18 of the 956 (1.9%) cases in our population, in 28% of which there was an associated COL4A1 or COL4A2 mutation. COL4A1 and COL4A2 gene mutations should be sought systematically in cases of severe and/or multifocal hemorrhagic or ischemic-hemorrhagic cerebral lesions, with or without schizencephaly or porencephaly. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Genetic Profiling of Idiopathic Antenatal Intracranial Haemorrhage: What We Know?

Intracranial hemorrhage (ICH) is reported in premature infants and rarely, in prenatal life. Fetal ICH can be accurately identified in utero and categorized by antenatal sonography and/or MRI. Infectious disease, maternal drug exposure, alloimmune thrombocytopenia, maternal trauma, coagulation disorders and twin-to-twin transfusion syndrome can cause fetal ICH. However, in many cases, the cause is not identified and a genetic disorder should be taken into consideration. We conducted a review of the literature to investigate what we know about genetic origins of fetal ICH. We conducted targeted research on the databases PubMed and EMBASE, ranging from 1980 to 2020. We found 311 studies and 290 articles were excluded because they did not meet the inclusion criteria, and finally, 21 articles were considered relevant for this review. Hemostatic, protrombotic, collagen and X-linked GATA 1 genes were reported in the literature as causes of fetal ICH. In cases of ICH classified as idiopathic, possible underlying genetic causes should be accounted for and investigated. The identification of ICH genetic causes can guide the counselling process with respect to the recurrence risk, in addition to producing relevant clinical data to the neonatologist for the optimal management and prompt treatment of the newborn.

Deletion in COL4A2 is associated with a three-generation variable phenotype: from fetal to adult manifestations

Genetic alterations in COL4A2 are less common than those of COL4A1 and their fetal phenotype has not been described to date. We describe a three-generation family with an intragenic deletion in COL4A2 associated with a prenatal diagnosis of recurrent fetal intracerebral hemorrhage (ICH), and a myriad of cerebrovascular manifestations. Exome sequencing, co-segregation analysis, and imaging studies were conducted on eight family members including two fetuses with antenatal ICH. Histopathological evaluation was performed on the terminated fetuses. An intragenic heterozygous pathogenic in-frame deletion; COL4A2, c.4151_4168del, (p.Thr1384_Gly1389del) was identified in both fetuses, their father with hemiplegic cerebral palsy (CP), as well as other family members. Postmortem histopathological examination identified microscopic foci of heterotopias and polymicrogyria. The variant segregated in affected individuals demonstrating varying degrees of penetrance and a wide phenotypic spectrum including periventricular venous hemorrhagic infarction causing hemiplegic CP, polymicrogyria, leukoencephalopathy, and lacunar stroke. We present radiographic, pathological, and genetic evidence of prenatal ICH and show, for what we believe to be the first time, a human pathological proof of polymicrogyria and heterotopias in association with a COL4A2 disease-causing variant, while illustrating the variable phenotype and partial penetrance of this disease. We highlight the importance of genetic analysis in fetal ICH and hemiplegic CP.

Identification of fibronectin 1 as a candidate genetic modifier in a Col4a1 mutant mouse model of Gould syndrome

Collagen type IV alpha 1 and alpha 2 (COL4A1 and COL4A2) are major components of almost all basement membranes. COL4A1 and COL4A2 mutations cause a multisystem disorder that can affect any organ but typically involves the cerebral vasculature, eyes, kidneys and skeletal muscles. In recent years, patient advocacy and family support groups have united under the name of Gould syndrome. The manifestations of Gould syndrome are highly variable, and animal studies suggest that allelic heterogeneity and genetic context contribute to the clinical variability. We previously characterized a mouse model of Gould syndrome caused by a Col4a1 mutation in which the severities of ocular anterior segment dysgenesis (ASD), myopathy and intracerebral hemorrhage (ICH) were dependent on genetic background. Here, we performed a genetic modifier screen to provide insight into the mechanisms contributing to Gould syndrome pathogenesis and identified a single locus [modifier of Gould syndrome 1 (MoGS1)] on Chromosome 1 that suppressed ASD. A separate screen showed that the same locus ameliorated myopathy. Interestingly, MoGS1 had no effect on ICH, suggesting that this phenotype could be mechanistically distinct. We refined the MoGS1 locus to a 4.3 Mb interval containing 18 protein-coding genes, including Fn1, which encodes the extracellular matrix component fibronectin 1. Molecular analysis showed that the MoGS1 locus increased Fn1 expression, raising the possibility that suppression is achieved through a compensatory extracellular mechanism. Furthermore, we found evidence of increased integrin-linked kinase levels and focal adhesion kinase phosphorylation in Col4a1 mutant mice that is partially restored by the MoGS1 locus, implicating the involvement of integrin signaling. Taken together, our results suggest that tissue-specific mechanistic heterogeneity contributes to the variable expressivity of Gould syndrome and that perturbations in integrin signaling may play a role in ocular and muscular manifestations.

COL4A1 mutation in an Indian child presenting as 'Cerebral Palsy' mimic

The COL4A1 gene (COL4A1) plays an important role in vascular basement membrane function and pathogenic mutations have been reported in mice and humans. The gene is expressed mainly in the human brain, eyes and kidneys. Pathogenic mutations result in a vast array of manifestations that can present throughout life including the foetal period. We present a case of an 11-year-old girl with right hemiparesis, congenital cataracts, epilepsy and magnetic resonance imaging (MRI) brain findings with a pathogenic COL4A1 mutation. Many of her clinical features are similar to those of a non-genetic cause of cerebral palsy highlighting the difficulties and delays in making this genetic diagnosis.

Neuropathology of genetically defined malformations of cortical development-A systematic literature review

AIMS

Malformations of cortical development (MCD) include a heterogeneous spectrum of clinical, imaging, molecular and histopathological entities. While the understanding of genetic causes of MCD has improved with the availability of next-generation sequencing modalities, genotype-histopathological correlations remain limited. This is the first systematic review of molecular and neuropathological findings in patients with MCD to provide a comprehensive overview of the literature.

METHODS

A systematic review was performed between November 2019 and February 2020. A MEDLINE search was conducted for 132 genes previously linked to MCD in order to identify studies reporting macroscopic and/or microscopic findings in patients with a confirmed genetic cause.

RESULTS

Eighty-one studies were included in this review reporting neuropathological features associated with pathogenic variants in 46 genes (46/132 genes, 34.8%). Four groups emerged, consisting of (1) 13 genes with well-defined histological-genotype correlations, (2) 27 genes for which neuropathological reports were limited, (3) 5 genes with conflicting neuropathological features, and (4) 87 genes for which no histological data were available. Lissencephaly and polymicrogyria were reported most frequently. Associated brain malformations were variably present, with abnormalities of the corpus callosum as most common associated feature.

CONCLUSIONS

Neuropathological data in patients with MCD with a defined genetic cause are available only for a small number of genes. As each genetic cause might lead to unique histopathological features of MCD, standardised thorough neuropathological assessment and reporting should be encouraged. Histological features can help improve the understanding of the pathogenesis of MCD and generate hypotheses with impact on further research directions.

The Role of Neuroimaging and Genetic Analysis in the Diagnosis of Children With Cerebral Palsy

Cerebral magnetic resonance imaging (MRI) is considered an important tool in the assessment of a child with cerebral palsy (CP), as it is abnormal in more than 80% of children with CP, disclosing the pathogenic pattern responsible for the neurological condition. MRI, therefore, is recommended as the first diagnostic step after medical history taking and neurological examination. With the advances in genetic diagnostics, the genetic contribution to CP is increasingly discussed, and the question arises about the role of genetic testing in the diagnosis of cerebral palsy. The paper gives an overview on genetic findings reported in CP, which are discussed with respect to the underlying brain pathology according to neuroimaging findings. Surveillance of Cerebral Palsy in Europe (SCPE) classifies neuroimaging findings in CP into five categories, which help to stratify decisions concerning genetic testing. Predominant white and gray matter injuries are by far predominant (accounting for around 50 and 20% of the findings). They are considered to be acquired. Here, predisposing genetic factors may play a role to increase vulnerability (and should especially be considered, when family history is positive and/or causative external factors are missing). In maldevelopments and normal findings (around 11% each), monogenic causes are more likely, and thus, genetic testing is clearly recommended. In the miscellaneous category, the precise nature of the MRI finding has to be considered as it could indicate a genetic origin.

Pregnancy in an Asymptomatic Woman with Porencephalic and Arachnoid Cysts

A 25-year-old woman presented to the obstetric clinic in her first pregnancy. The patient was accompanied by her mother who reported an episode of intracerebral hemorrhage after birth and also remembered access to the emergency department after generalized tonic-clonic seizure as an infant. She was not able to describe the therapy for seizure preventions and even when and why it was suspended, but she affirmed that no residual neurological consequences were detected in the following years. Actually, the pregnant woman was in good health without neurological symptoms nor assumed any therapy. A neurologist reviewed the patient's CT scan in which arachnoid cyst and porencephalic cyst were evident, and he assessed that no abnormalities were found in motor, sensory, and mental state examination. EEG did not show any epileptiform or seizure-like activity. No antiepileptic drug was prescribed due to the absence of symptoms since many years. The patient had no neurological symptoms during pregnancy or obstetric complications and delivered at term a healthy baby through a caesarean section. She breastfed, and after two years, the patient and the baby are healthy. The association of porencephalic and arachnoid cyst in pregnancy is an extremely rare neurological condition that needs a multidisciplinary counseling in pregnancy, but an uneventful course is possible.

Neuropsychological presentation of colpocephaly and porencephaly with symptom onset in adulthood

Colpocephaly is a form of congenital ventriculomegaly while porencephaly describes any full-thickness defect within the brain which usually presents as a cystic structure. Postulated aetologies include intrauterine/perinatal injuries, genetic disorders, and morphogenesis error. Colopocephaly and porencephaly is typically diagnosed in infancy while diagnosis in adulthood is exceptionally rare. We report a case of co-existence of colpocephaly with porencephaly diagnosed incidentally in a 54-year-old male presenting with subtle cognitive and neurologic abnormalities. Neuropsychological assessment revealed weaknesses in executive functions, processing speed, and language.To our knowledge, this is the only reported case of dual incidental findings of porencephaly and colpocephaly in an adult.

Novel COL4A1 mutations identified in infants with congenital hemolytic anemia in association with brain malformations

Genetic causes of undiagnosed hemolytic anemia in nineteen patients were analyzed by whole-exome sequencing, and novel COL4A1 variants were identified in four patients (21%). All patients were complicated with congenital malformations of the brain, such as porencephaly or schizencephaly. In these patients, hemolysis became less severe within 2 months after birth, and red cell transfusion was no longer required after 50 days, whereas chronic hemolysis continued.

Role of child neurologists and neurodevelopmentalists in the diagnosis of cerebral palsy: A survey study

OBJECTIVE

To contextualize the role of child neurologists and neurodevelopmentalists (CNs/NDDs) in cerebral palsy (CP) care, we review the changing landscape of CP diagnosis and survey stakeholder CNs/NDDs regarding their roles in CP care.

METHODS

The optimal roles of the multiple specialties involved in CP care are currently unclear, particularly regarding CP diagnosis. We developed recommendations regarding the role of CNs/NDDs noting (1) increasing complexity of CP diagnosis given a growing number of genetic etiologies and treatable motor disorders that can be misdiagnosed as CP and (2) the views of a group of physician stakeholders (CNs/NDDs from the Child Neurology Society Cerebral Palsy Special Interest Group).

RESULTS

CNs/NDDs felt that they were optimally suited to diagnose CP. Many (76%) felt that CNs/NDDs should always be involved in CP diagnosis. However, 42% said that their patients with CP were typically not diagnosed by CNs/NDDs, and 18% did not receive referrals to establish the diagnosis of CP at all. CNs/NDDs identified areas of their expertise critical for CP diagnosis including knowledge of the neurologic examination across development and early identification of features atypical for CP. This contrasts with their views on CP management, where CNs/NDDs felt that they could contribute to the medical team, but were necessary primarily when neurologic coexisting conditions were present.

DISCUSSION

Given its increasing complexity, we recommend early referral for CP diagnosis to a CN/NDD or specialist with comparable expertise. This contrasts with current consensus guidelines, which either do not address or do not recommend specific specialist referral for CP diagnosis.

Expanding the phenotype of COL4A1-related disorders-Four novel variants

OBJECTIVE

COL4A1 variant causes severe central nervous system (CNS) anomalies, including hydranencephaly. However, the pathogenic mechanism underlying the COL4A1 phenotype remains unclear. Here, we report de novo COL4A1 variants in four Japanese patients with typical or rare CNS involvement and exhibiting diverse phenotypes.

METHODS

We identified and enrolled four patients with white matter abnormalities and cerebral structural defects suggestive of cerebrovascular disease. Genetic analysis was performed using panel sequencing.

RESULTS

All the patients were perinatally asymptomatic during the infantile period but exhibited developmental delay and growth retardation later. All the patients exhibited CNS symptoms, including psychomotor disability, spastic paralysis, and epilepsy. Brain magnetic resonance imaging revealed hydranencephaly (n = 1), ventriculomegaly (n = 4) associated with cerebral hemorrhage, and atretic encephalocele (n = 1). Three patients had developed congenital cataract, while two had hematuria. We identified two COL4A1 missense variants [exon32:c.2555G > A p.(Gly852Asp), exon40:c.3407G > A p.(Gly1136Asp)] and two in frame variants [exon32:c.2603_2609delinsATCCTGA p.(Ala868_Gly870delinsAspProGlu), exon36:c.3054delinsTGTAGAT p.(Leu1018delinsPheValAsp)]. The in frame variants were associated with severe CNS anomalies, hydranencephaly, and severe ventriculomegaly. Atretic encephalocele has never been reported in individuals with COL4A1 variants.

CONCLUSIONS

Our findings suggest that COL4A1 variants cause variable CNS symptoms. Association between clinical phenotypes and each COL4A1 variant would clarify their underlying etiologies.

Unilateral right closed-lip schizencephaly

Schizencephaly is a rare central nervous system (CNS) malformation secondary to neuronal migration defects. The pathogenesis is complex and is secondary to environmental and genetic factors. Clinically, the majority of patients present with varying degrees of motor and psychological disturbances. Imaging plays a cornerstone in the diagnosis by identifying the characteristic lesional features and recognising other associated abnormalities such as an absent septum pellucidum and corpus callosum dysgenesis. Here, we present a male paediatric case who presented with an interestingly asymptomatic unilateral right closed-lip schizencephaly and review the aetiology, clinical presentation and imaging characteristics of the disease and associated literature.

p.Gly743Val Mutation in COL4A1 Is Responsible for Familial Porencephaly and Severe Hypermetropia

COL4A1 is an essential component for basal membrane stability. Exon mutations of the COL4A1 genes are responsible for a broad spectrum of cerebral, ocular, and systemic manifestations. We describe here the phenotype of a likely pathogenic gene variant, p.Gly743Val, which is responsible for a missense mutation in the COL4A1 gene exon 30 in a three generation family with severe hypermetropia and highly penetrant porencephaly in the absence of systemic manifestations. This report highlights both the broad spectrum of COL4A1 mutations and the yield of testing the COL4A1 gene in familial ophthalmological and brain disorders.

Prenatal clinical manifestations in individuals with COL4A1/2 variants

BACKGROUND

Variants in the type IV collagen gene (COL4A1/2) cause early-onset cerebrovascular diseases. Most individuals are diagnosed postnatally, and the prenatal features of individuals with COL4A1/2 variants remain unclear.

METHODS

We examined COL4A1/2 in 218 individuals with suspected COL4A1/2-related brain defects. Among those arising from COL4A1/2 variants, we focused on individuals showing prenatal abnormal ultrasound findings and validated their prenatal and postnatal clinical features in detail.

RESULTS

Pathogenic COL4A1/2 variants were detected in 56 individuals (n=56/218, 25.7%) showing porencephaly (n=29), schizencephaly (n=12) and others (n=15). Thirty-four variants occurred de novo (n=34/56, 60.7%). Foetal information was available in 47 of 56 individuals, 32 of whom (n=32/47, 68.1%) had one or more foetal abnormalities. The median gestational age at the detection of initial prenatal abnormal features was 31 weeks of gestation. Only 14 individuals had specific prenatal findings that were strongly suggestive of features associated with COL4A1/2 variants. Foetal ventriculomegaly was the most common initial feature (n=20/32, 62.5%). Posterior fossa abnormalities, including Dandy-Walker malformation, were observed prenatally in four individuals. Regarding extrabrain features, foetal growth restriction was present in 16 individuals, including eight individuals with comorbid ventriculomegaly.

CONCLUSIONS

Prenatal observation of ventriculomegaly with comorbid foetal growth restriction should prompt a thorough ultrasound examination and COL4A1/2 gene testing should be considered when pathogenic variants are strongly suspected.

Phenotypic characterization of COL4A1-related West syndrome

Collagen type IV, alpha-1 (COL4A1) variants can cause cerebrovascular diseases, such as porencephaly and cerebral hemorrhage, in addition to other autosomal dominant hereditary diseases. Patients with COL4A1 variants can present with epilepsy, most commonly focal epilepsy. In this paper, we present five patients, three of whom were examined by the authors, and two who were previously reported. Clinically, these five patients were characterized by the presence of West syndrome (WS), periventricular leukomalacia (PVL), and microcephaly, but none had a history of premature birth or hypoxic ischemic encephalopathy (HIE). Genetic testing results indicated that all patients had heterozygous variants of COL4A1. Genetic testing for the COL4A1 variants should be considered when a patient without a history of prematurity or HIE develops WS with PVL and microcephaly.

Whole genome sequencing unveils genetic heterogeneity in optic nerve hypoplasia

Optic nerve hypoplasia (ONH) is a congenital malformation with a reduced number of retinal ganglion cell axons in a thin optic nerve. It is a common cause of visual impairment in children and ONH is associated with neurodevelopmental disorders, pituitary hormone deficiencies, and brain malformations. In most cases, the aetiology is unknown, but both environmental factors and genetic causes have been described. This study aimed to identify genetic variants underlying ONH in a well-characterised cohort of individuals with ONH. We performed array comparative genomic hybridization and whole genome sequencing in 29 individuals with ONH. Rare variants were verified by Sanger sequencing and inheritance was assessed in parental samples. We identified 11 rare single nucleotide variants (SNVs) in ten individuals, including a homozygous variant in KIF7 (previously associated with Joubert syndrome), a heterozygous de novo variant in COL4A1 (previously described in an individual with porencephaly), and a homozygous variant in COL4A2. In addition, one individual harboured a heterozygous variant in OPA1 and a heterozygous variant in COL4A1, both were inherited and assessed as variants of unknown clinical significance. Finally, a heterozygous deletion of 341 kb involving exons 7-18 of SOX5 (associated with Lamb-Schaffer syndrome) was identified in one individual. The overall diagnostic yield of pathogenic or likely pathogenic variants in individuals with ONH using whole genome sequencing was 4/29 (14%). Our results show that there is a genetic heterogeneity in ONH and indicate that genetic causes of ONH are not rare. We conclude that genetic testing is valuable in a substantial proportion of the individuals with ONH, especially in cases with non-isolated ONH.

Persistent falcine sinus with temporo-occipital schizencephaly: case report with a review of literature in relation to the undeveloped vein of Galen and/or straight sinus

Falcine sinus is a normal midline embryonic venous sinus present in the fetal brain and usually disappears by birth. Persistent falcine sinus (PFS) has been reported as a normal variant or along with vein of Galen (VOG) malformation, encephalocele, and other abnormalities. Schizencephaly, either closed or open type, has been reported with other associated vascular anomalies. We report a 22-month-old child, who presented with delayed milestones and referred for magnetic resonance (MR) imaging, and the child was found to have PFS with associated bilateral temporo-occipital closed-lip schizencephaly, hippocampal abnormalities, falco-tentorial dehiscence, and white matter abnormalities. The vein of Galen and straight sinus were absent, and the internal cerebral veins were seen draining into superior sagittal sinus via the falcine sinus. These set of abnormalities are unique from abnormalities reported previously in association with the falcine sinus.

Clinical Implementation of Targeted Gene Sequencing for Malformation of Cortical Development

BACKGROUND

Malformations of cortical development comprise phenotypically heterogeneous conditions, and the diagnostic value of genetic testing in blood still remains to be elucidated. We used targeted gene sequencing to identify malformations of cortical development caused by germline mutations and characteristics associated with pathogenic mutations.

METHODS

A total of 81 patients with malformations of cortical development were included. Genomic DNA was isolated from peripheral blood. Ninety-six genes were assessed using a targeted next-generation sequencing panel. Single-nucleotide variants and exonic and chromosomal copy number variations were examined with our customized pipeline.

RESULTS

Genetic causes were identified from blood in 19 (23.5%) patients with malformations of cortical development; 14 patients had pathogenic or likely pathogenic single-nucleotide variants in seven genes, including DCX (n = 5), DEPDC5 (n = 2), PAFAH1B1 (n = 3), TUBA1A (n = 1), TUBA8 (n = 1), TUBB2B (n = 1), and TUBB3 (n = 1). Five patients had pathogenic copy number variations. Multifocal involvement of the lesion (tangential distribution, P < 0.001) and concurrent involvement of multiple structures such as the cortex, white matter, and ventricle (radial distribution, P = 0.003) were more commonly found in patients with identified genetic causes. Intellectual disability was also more commonly associated with pathogenic mutations (P = 0.048). In a multivariable regression analysis, both tangential and radial radiological distribution of malformations of cortical development were independently associated with positive germline test results.

CONCLUSION

We identified germline mutations in almost one-fourth of our patients with malformations of cortical development by using targeted gene sequencing. Germline abnormalities were more likely found in patients who had multifocal malformations of cortical development.

Life-threatening muscle complications of COL4A1-related disorder

COL4A1-related disorder is recognized as a systemic disease because the alpha 1 chain of type IV collagen, encoded by COL4A1, is essential for basement membrane stability. However, muscular manifestations related to this disorder are rarely reported. We report the case of a 2-year-old boy with porencephaly, who harbored a de novo COL4A1 mutation of c.1853G > A, p. (Gly618Glu) and exhibited recurrent rhabdomyolysis with viral or bacterial infections. Moreover, he developed obstructive hypertrophic cardiomyopathy which required surgical intervention. Skeletal muscle biopsy revealed findings compatible with fiber-type disproportion. Ultrastructural study demonstrated the similar findings previously reported in mice with Col4a1 mutation including collagen disarray and reduction of electron density in the basement membrane of capillary endothelial cells and muscle fibers. Dilated endoplasmic reticulum in the capillary endothelial cells is also noted. This report adds another disease spectrum of COL4A1 mutation which include porencephaly, hypertrophic cardiomyopathy, rhabdomyolysis and fiber-type disproportion.

De novo p.G696S mutation in COL4A1 causes intracranial calcification and late-onset cerebral hemorrhage: A case report and review of the literature

BACKGROUND

The collagen type IV alpha 1 chain (COL4A1) is an essential component of the basement membrane in small vessels. Pathogenic variants in COL4A1 cause perinatal cerebral hemorrhages in an autosomal-dominant fashion. However, little is known about the long-term outcomes of patients with mildly affecting COL4A1 mutations.

CASE REPORT

We report a 17-year-old boy, who presented with recurrent intracranial hemorrhages in the periventricular white matter. He had been followed-up as a child with cerebral palsy bearing intracranial calcifications, developmental delay and epilepsy. Screening tests in infancy provided negative results for intrauterine infections. Severe motor and cognitive deficits persisted after admission. Carbazochrome was introduced on day 19 of admission, which appeared to prevent extension and reactivation of cerebral hemorrhages for over 6 months after discharge.

RESULTS

Targeted sequencing of NOTCH3 and TREX1 excluded causal mutations in these genes. The whole-exome sequencing revealed that he carried a de novo mutation in COL4A1 (p.Gly696Ser). An overview of the literature for 345 cases with COL4A1 mutations supported evidence that p.Gly696Ser is associated with the unique phenotype of late-onset hemorrhage among patients with COL4A1-associated cerebral angiopathy.

CONCLUSIONS

This case first demonstrates that infants with COL4A1-associated leukoencephalopathy and calcifications have a risk for developing the rupture of small vessels in the cerebral white matter after 10 years of age.