Multiorgan manifestations of COL4A1 and COL4A2 variants and proposal for a clinical management protocol.

COL4A1/2 variants are associated with highly variable multiorgan manifestations. Depicting the whole clinical spectrum of COL4A1/2-related manifestations is challenging, and there is no consensus on management and preventative strategies. Based on a systematic review of current evidence on COL4A1/2-related disease, we developed a clinical questionnaire that we administered to 43 individuals from 23 distinct families carrying pathogenic variants. In this cohort, we extended ophthalmological and cardiological examinations to asymptomatic individuals and those with only limited or mild, often nonspecific, clinical signs commonly occurring in the general population (i.e., oligosymptomatic). The most frequent clinical findings emerging from both the literature review and the questionnaire included stroke (203/685, 29.6%), seizures or epilepsy (199/685, 29.0%), intellectual disability or developmental delay (168/685, 24.5%), porencephaly/schizencephaly (168/685, 24.5%), motor impairment (162/685, 23.6%), cataract (124/685, 18.1%), hematuria (63/685, 9.2%), and retinal arterial tortuosity (58/685, 8.5%). In oligosymptomatic and asymptomatic carriers, ophthalmological investigations detected retinal vascular tortuosity (5/13, 38.5%), dysgenesis of the anterior segment (4/13, 30.8%), and cataract (2/13, 15.4%), while cardiological investigations were unremarkable except for mild ascending aortic ectasia in 1/8 (12.5%). Our multimodal approach confirms highly variable penetrance and expressivity in COL4A1/2-related conditions, even at the intrafamilial level with neurological involvement being the most frequent and severe finding in both children and adults. We propose a protocol for prevention and management based on individualized risk estimation and periodic multiorgan evaluations.

Col4a2 Mutations Contribute to Infantile Epileptic Spasm Syndrome and Neuroinflammation.

There are more than 70 million people worldwide living with epilepsy, with most experiencing the onset of epilepsy in childhood. Despite the availability of more than 20 anti-seizure medications, approximately 30% of epilepsy patients continue to experience unsatisfactory treatment outcomes. This situation places a heavy burden on patients' families and society. Childhood epilepsy is a significant chronic neurological disease that is closely related to genetics. Col4a2, the gene encoding the α2 chain of type IV collagen, is known to be associated with multiple diseases due to missense mutations. The Col4a2 variant of collagen type IV is associated with various phenotypes, including prenatal and neonatal intracranial hemorrhage, porencephaly, porencephaly with cataracts, focal cortical dysplasia, schizencephaly, strokes in childhood and adolescence, and sporadic delayed hemorrhagic stroke. Although epilepsy is recognized as a clinical manifestation of porencephaly, the specific mechanism of Col4a2-related epileptic phenotypes remains unclear. A total of 8 patients aged 2 years and 2 months to 18 years who were diagnosed with Col4a2-related infantile epileptic spasm syndrome were analyzed. The seizure onset age ranged from 3 to 10 months. Initial EEG results revealed hypsarrhythmia or multiple and multifocal sharp waves, spike waves, sharp slow waves, or spike slow waves. Elevated levels of the cytokines IL-1ß (32.23±12.58 pg/ml) and IL-6 (45.12±16.03 pg/ml) were detected in the cerebrospinal fluid of these patients without any signs of infection. Following antiseizure treatment, decreased IL-1ß and IL-6 levels in the cerebrospinal fluid were noted when seizures were under control. Furthermore, we aimed to investigate the role of Col4a2 mutations in the development of epilepsy. Through the use of immunofluorescence assays, ELISA, and Western blotting, we examined astrocyte activity and the expression of inflammatory cytokines such as IL-1ß, IL-6, and TNF-α after overexpressing an unreported Col4a2 (c.1838G>T) mutant in CTX-TNA cells and primary astrocytes. We found that the levels of the inflammatory factors IL-1ß, IL-6, and TNF-α were increased in both CTX-TNA cells (ELISA: p = 0.0087, p<0.001, p<0.001, respectively) and primary astrocytes (ELISA: p = 0.0275, p<0.001, p<0.001, respectively). Additionally, we conducted a preliminary investigation of the role of the JAK/STAT pathway in Col4a2 mutation-associated epilepsy. Col4a2 mutation stimulated astrocyte activation, increasing iNOS, COX-2, IL-1ß, IL-6, and TNF-α levels in both CTX-TNA cells and primary astrocytes. This mutation also activated the JAK/STAT signaling pathway, leading to increased phosphorylation of JAK2 and STAT3. Treatment with the JAK/STAT inhibitor WP1066 effectively counteracted this effect in primary astrocytes and CTX-TNA cells. To date, the genes who mutations are known to cause developmental and epileptic encephalopathies (DEEs) are predominantly grouped into six subtypes according to function. Our study revealed that an unreported mutation site Col4a2Mut (c.1838G>T) of which can cause neuroinflammation, may be a type VII DEE-causing gene.

Extracellular matrix of ameloblastoma-derived negatively regulates osteogenic differentiation.

OBJECTIVE: To investigate the effects of key pathogenic genes involved in the development of jaw ameloblastoma (AB) and its associated extracellular matrix (ECM) on osteogenic differentiation in order to provide a theoretical foundation for future research into bone aggressiveness of AB. METHODS: The essential genes were identified by five AB patients for whole-exome sequencing and the microarray datasets GES38494 and GES132472. Moreover, the expression of key genes and their encoded proteins in AB tissues was explored. In addition, AB-derived the decellularized ECM (ABdECM) tissues were generated by the decellularization technique. Furthermore, the osteogenic development of periodontal ligament stem cells (PDLSCs) was mimicked by simulating the effects of the AB tumor microenvironment (TME). RESULTS: The AB essential genes including COL1A2, COL4A2, FBN1, and HPSE were discovered. Among them, the expression of HPSE was down-regulated, while that of COL1A2, COL4A2, and FBN1 was noticeably upregulated in AB compared with normal gingival tissues of the jaws. In vitro osteogenic differentiation of PDLSCs was suppressed by the ABdECM. CONCLUSIONS: Abnormal ECM proteins encoded by COL4A2, COL1A2, FBN1, and HPSE genes can cause disturbance in the ECM environment of AB and promote bone resorption.

COL4A1 Mutations Cause Neuromuscular Disease with Tissue-Specific Mechanistic Heterogeneity.

Collagen type IV alpha 1 and alpha 2 chains form heterotrimers ([α1(IV)]2α2(IV)) that represent a fundamental basement membrane constituent. Dominant COL4A1 and COL4A2 mutations cause a multisystem disorder that is marked by clinical heterogeneity and variable expressivity and that is generally characterized by the presence of cerebrovascular disease with ocular, renal, and muscular involvement. Despite the fact that muscle pathology is reported in up to one-third of individuals with COL4A1 and COL4A2 mutations and in animal models with mutations in COL4A1 and COL4A2 orthologs, the pathophysiological mechanisms underlying COL4A1-related myopathy are unknown. In general, mutations are thought to impair [α1(IV)]2α2(IV) secretion. Whether pathogenesis results from intracellular retention, extracellular deficiency, or the presence of mutant proteins in basement membranes represents an important gap in knowledge and a major obstacle for developing targeted interventions. We report that Col4a1 mutant mice develop progressive neuromuscular pathology that models human disease. We demonstrate that independent muscular, neural, and vascular insults contribute to neuromyopathy and that there is mechanistic heterogeneity among tissues. Importantly, we provide evidence of a COL4A1 functional subdomain with disproportionate significance for tissue-specific pathology and demonstrate that a potential therapeutic strategy aimed at promoting [α1(IV)]2α2(IV) secretion can ameliorate or exacerbate myopathy in a mutation-dependent manner. These data have important translational implications for prediction of clinical outcomes based on genotype, development of mechanism-based interventions, and genetic stratification for clinical trials. Collectively, our data underscore the importance of the [α1(IV)]2α2(IV) network as a multifunctional signaling platform and show that allelic and tissue-specific mechanistic heterogeneities contribute to the variable expressivity of COL4A1 and COL4A2 mutations.

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.

A Study of Associations Between rs9349379 (PHACTR1), rs2891168 (CDKN2B-AS), rs11838776 (COL4A2) and rs4880 (SOD2) Polymorphic Variants and Coronary Artery Disease in Iranian Population.

Recent genome-wide association studies reported the association of polymorphic alleles of PHACTR1 (rs9349379 (G)), CDDKN2B-AS1 (rs2891168 (G)), COL4A2 (rs11838776 (A)) and SOD2 (rs4880 (T)) with increased risk of coronary artery disease (CAD). The aim of our study was to assess the association of genetic variants with risk of CAD and its severity and in Southeast Iranian population. This study was examined in 250 CAD-suspected patients (mean age 53.49 ± 6.9 years) and 250 healthy individuals (mean age 52.96 ± 5.9 years). The Taqman SNP genotyping assay was used for genotyping of rs9349379 and rs2891168 variants. Tetra-primer Amplified refractory mutation system-PCR (Tetra-primer ARMS-PCR) was employed for rs11838776 and rs4880. Multivariate logistic regression analyses indicated that the G allele of rs9349379 and rs2891168 were associated with increased risk of CAD. The GG homozygous genotype of rs9349379 and rs2891168 had also been associated with risk of CAD. Additionally, the AG genotype of rs2891168 was associated with CAD. The significance of association of rs2891168 (G, GG, AG) increases with severity of CAD; but the rs9349379 (G, GG) have shown reverse association with severity of CAD. The genetic variants of COL4A2 (rs11838776) and SOD2 (rs4880) reflected no association with CAD in Southeast Iranian population. The findings of this study revealed that the PHACTR1 (rs9349379) and CDKN2B-AS1 (rs2891168) genetic variants might serve as genetic risk factor in CAD.

Next-generation sequencing in a large pedigree segregating visceral artery aneurysms suggests potential role of COL4A1/COL4A2 in disease etiology.

BACKGROUND: Visceral artery aneurysms (VAAs) can be fatal if ruptured. Although a relatively rare incident, it holds a contemporary mortality rate of approximately 12%. VAAs have multiple possible causes, one of which is genetic predisposition. Here, we present a striking family with seven individuals affected by VAAs, and one individual affected by a visceral artery pseudoaneurysm. METHODS: We exome sequenced the affected family members and the parents of the proband to find a possible underlying genetic defect. As exome sequencing did not reveal any feasible protein-coding variants, we combined whole-genome sequencing of two individuals with linkage analysis to find a plausible non-coding culprit variant. Variants were ranked by the deep learning framework DeepSEA. RESULTS: Two of seven top-ranking variants, NC_000013.11:g.108154659C>T and NC_000013.11:g.110409638C>T, were found in all VAA-affected individuals, but not in the individual affected by the pseudoaneurysm. The second variant is in a candidate cis-regulatory element in the fourth intron of COL4A2, proximal to COL4A1. CONCLUSIONS: As type IV collagens are essential for the stability and integrity of the vascular basement membrane and involved in vascular disease, we conclude that COL4A1 and COL4A2 are strong candidates for VAA susceptibility genes.

Bilateral Non-Arteritic Anterior Ischaemic Optic Neuropathy in a Patient with a COL4A2 Mutation.

Non-arteritic anterior ischaemic optic neuropathy (NAION) is a common cause of vision loss in adults and is thought to be due to compromised perfusion to the optic nerve head. Patients with NAION in one eye are at risk of recurrence in the fellow eye. We report a case of sequential, bilateral NAION in a patient who was found to have a COL4A2 mutation. COL4A2 encodes a subunit of the collagen 4 protein, the major component of the human basement membranes, and has several known cerebrovascular and ocular associations.

Intracerebral hemorrhage in a neonate with an intragenic COL4A2 duplication.

Intracerebral hemorrhage is rare in term born neonates. Besides several non-genetic risk factors, pathogenic variants in COL4A1 and COL4A2 have been described to play a role in the pathophysiology of neonatal intracerebral hemorrhage. To the best of our knowledge, no intragenic COL4A2 duplications have been reported in humans to date. We report a neonate with intracerebral hemorrhage and a de novo intragenic COL4A2 duplication. Although it is not clear yet whether this genetic factor fully explains the clinical phenotype, it may have contributed at least as a risk factor for cerebral hemorrhage. Screening for intragenic COL4A1 and COL4A2 duplications as part of collagen IV diagnostics should be considered as part of the fetal and neonatal work-up for unexplained cerebral hemorrhages and to collect more evidence of the pathogenicity of this genetic mechanism.

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.

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.

A Novel COL4A2 Mutation Associated with Recurrent Strokes.

Mutations in type four collagens, specifically COL4A1 and COL4A2, have been associated with cerebral small vessel disease (SVD), defined as lacunar infarcts, deep intracerebral hemorrhages (ICH), and leukoaraiosis. We present a case of a man with recurrent cerebral infarcts, related to a novel COL4A2 mutation, the p.A1534S variant. Magnetic resonance imaging demonstrated multiple lacunar infarcts, numerous deep and lobar microhemorrhages and advanced leukoaraiosis. Evaluation for COL4A2 mutations should be considered when suspecting a genetic cerebral small vessel disease.

Severity of arterial defects in the retina correlates with the burden of intracerebral haemorrhage in COL4A1-related stroke.

Mutations in the α1 (COL4A1) or α2 (COL4A2) chains of collagen type IV, a major component of the vascular basement membrane, cause intracerebral haemorrhages with variable expressivity and reduced penetrance by mechanisms that remain poorly understood. Here we sought to investigate the cellular mechanisms of COL4A1-related intracerebral haemorrhage and identify a marker for haemorrhage risk stratification. A combination of histological, immunohistochemical, and electron microscopy analyses were used to analyse the brain parenchyma, cerebrovasculature, and retinal vessels of mice expressing the disease-causing COL4A1 p.G498V mutation. Mutant mice developed cerebral microhaemorrhages and macroscopic haemorrhages (macrohaemorrhages), the latter with reduced penetrance, mimicking the human disease. Microhaemorrhages that occurred in early postnatal life were associated with a transient, generalized increase in blood-brain barrier permeability at the level of capillaries. Macrohaemorrhages, which occurred later in life, originated from deep brain arteries with focal loss of smooth muscle cells. Similar smooth muscle cell loss was detected in retinal arteries, and a time-course analysis of arterial lesions showed that smooth muscle cells are recruited normally in arterial wall during development, but undergo progressive apoptosis-mediated degeneration. By assessing in parallel the extent of these retinal arterial lesions and the presence/absence of macrohaemorrhages, we found that the arterial lesion load in the retina is strongly correlated with the burden of macrohaemorrhages. We conclude that microhaemorrhages and macrohaemorrhages are driven by two distinct mechanisms. Moreover, smooth muscle cell degeneration is a critical factor underlying the partial penetrance of COL4A1-related macrohaemorrhages, and retinal imaging is a promising tool for identifying high-risk patients. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Alpha-synuclein deregulates the expression of COL4A2 and impairs ER-Golgi function.

Alpha-synuclein (aSyn) is the major protein component of Lewy bodies and Lewy neurites, the typical pathological hallmarks in Parkinson's disease (PD) and Dementia with Lewy bodies. aSyn is capable of inducing transcriptional deregulation, but the precise effect of specific aSyn mutants associated with familial forms of PD, remains unclear. Here, we used transgenic mice overexpressing human wild-type (WT) or A30P aSyn to compare the transcriptional profiles of the two animal models. We found that A30P aSyn promotes strong transcriptional deregulation and increases DNA binding. Interestingly, COL4A2, a major component of basement membranes, was found to be upregulated in both A30P aSyn transgenic mice and in dopaminergic neurons expressing A30P aSyn, suggesting a crucial role for collagen related genes in aSyn-induced toxicity. Finally, we observed that A30P aSyn alters Golgi morphology and increases the susceptibility to endoplasmic reticulum (ER) stress in dopaminergic cells. In total, our findings provide novel insight into the putative role of aSyn on transcription and on the molecular mechanisms involved, thereby opening novel avenues for future therapeutic interventions in PD and other synucleinopathies.

Novel COL4A2 variant in a large pedigree: Consequences and dilemmas.

Pathogenic COL4A2 variants cause abnormalities in collagen production and can have serious implications for a range of organ systems, most notably the brain. Herein, we describe a large family of first-degree relatives affected by a novel heterozygous variant in COL4A2 (c.3490G.A). A wide disease spectrum is described, from asymptomatic to symptomatic, including 2 children with porencephaly and co-existing juvenile idiopathic polyarthritis. During a subsequent pregnancy, antenatal testing identified a positive fetus. In view of the literature, we review management and genetic counselling dilemmas.

A mutation in COL4A2 causes autosomal dominant porencephaly with cataracts.

Mutations in COL4A1 are well described and result in brain abnormalities manifesting with severe neurological deficits including cerebral palsy, intellectual disability, and focal epilepsy. Families with mutations in COL4A2 are now emerging with a similar phenotype. We describe a family with an autosomal dominant disorder comprising porencephaly, focal epilepsy, and lens opacities, which was negative for mutations in COL4A1. Using whole exome sequencing of three affected individuals from three generations, we identified a rare variant in COL4A2. This COL4A2 (c.2399G>A, p.G800E, CCDS41907.1) variant was predicted to be damaging by multiple bioinformatics tools and affects an invariable glycine residue that is essential for the formation of collagen IV heterotrimers. The cataracts identified in this family expand the phenotypic spectrum associated with mutations in COL4A2 and highlight the increasing overlap with phenotypes associated with COL4A1 mutations.

De Novo interstitial deletion 13q33.3q34 in a male patient with double outlet right ventricle, microcephaly, dysmorphic craniofacial findings, and motor and developmental delay.

We describe a 6-year-old male, diagnosed at birth with double outlet right ventricle (DORV), anterior aorta, multiple ventricular septal defects, pulmonary stenosis, microcephaly and mildly dysmorphic craniofacial findings. Chromosomal analysis showed a normal male karyotype but on subsequent array comparative genomic hybridization (array CGH) analysis a de novo 2.5 Mb loss in chromosome 13q at 13q33.3q34, together with an inherited gain at 4p12, were detected. The propositus underwent placement of a Blalock Taussig shunt and subsequently a Glenn and Fontan operation was performed. In this report we propose that COL4A1 and COL4A2 may be candidate genes for congenital heart disease (CHD) in individuals with a deletion in 13q within the 6Mb critical region for cardiac development proposed by Huang et al., [2012].

Type IV Collagens and Basement Membrane Diseases: Cell Biology and Pathogenic Mechanisms.

Basement membranes are highly specialized extracellular matrices. Once considered inert scaffolds, basement membranes are now viewed as dynamic and versatile environments that modulate cellular behaviors to regulate tissue development, function, and repair. Increasing evidence suggests that, in addition to providing structural support to neighboring cells, basement membranes serve as reservoirs of growth factors that direct and fine-tune cellular functions. Type IV collagens are a major component of all basement membranes. They evolved along with the earliest multicellular organisms and have been integrated into diverse fundamental biological processes as time and evolution shaped the animal kingdom. The roles of basement membranes in humans are as complex and diverse as their distributions and molecular composition. As a result, basement membrane defects result in multisystem disorders with ambiguous and overlapping boundaries that likely reflect the simultaneous interplay and integration of multiple cellular pathways and processes. Consequently, there will be no single treatment for basement membrane disorders, and therapies are likely to be as varied as the phenotypes. Understanding tissue-specific pathology and the underlying molecular mechanism is the present challenge; personalized medicine will rely upon understanding how a given mutation impacts diverse cellular functions.

Missense mutations in exon 2 of the MED12 gene are involved in IGF-2 overexpression in uterine leiomyoma.

Uterine leiomyoma (UL), the most common benign tumour found in females, is associated with many recurrent genetic aberrations, such as translocations, interstitial deletions and specific germline mutations. Among these, mutations affecting exon 2 of the mediator complex subunit 12 (MED12) gene are commonly detected in the majority of ULs. Mutational analysis of the MED12 gene, performed on 36 UL samples, revealed that 12 leiomyomas (33.4%) exhibited heterozygous missense mutations in codon 44 of exon 2 of the MED12 gene, four leiomyomas (11.1%) showed internal in-frame deletions, and two leiomyomas (5.5%) exhibited deletions involving intron 1-exon 2 junction, which caused a predicted loss of the splice acceptor. No mutations were detected in uterine myometrium (UM) and pseudocapsule (PC) samples, including those from women with a MED12 mutation in UL. These data showed that the PC is a healthy tissue that surrounds the UL to maintain UM integrity. Analysis of insulin-like growth factor 2 (IGF-2) and collagen type IV alpha 2 (COL4A2) mRNA expression levels in the same set of ULs revealed that only those with MED12 missense mutations expressed significantly higher levels of IGF-2 mRNA. In contrast, MED12 gene status does not appear to affect mRNA expression levels of the COL4A2 gene. On the basis of this finding, we suggest that the MED12 status stratifies the ULs into two mutually exclusive pathways of leiomyoma genesis, one with IGF-2 overexpression and the other with no IGF-2 activation. The occurrence of IGF-2 overexpression could be therapeutically targeted for the non-surgical treatment of leiomyomas.

Identification of a novel intronic variant in COL4A2 gene associated with fetal severe cerebral encephalomalacia and subdural hemorrhage.

BACKGROUND: Genetic variants in COL4A2 are less common than those of COL4A1 and their fetal clinical phenotype has not been well described to date. We present a fetus from China with an intronic variant in COL4A2 associated with a prenatal diagnosis of severe cerebral encephalomalacia and subdural hemorrhage. METHODS: Whole exome sequencing (WES) was applied to screen potential genetic causes. Bioinformatic analysis was performed to predict the pathogenicity of the variant. In in vitro experiment, the minigene assays were performed to assess the variant's effect. RESULTS: In this proband, we observed ventriculomegaly, subdural hemorrhage, and extensive encephalomalacia that initially suggested cerebral hypoxic-ischemic and/or hemorrhagic lesions. WES identified a de novo heterozygous variant c.549 + 5G > A in COL4A2 gene. This novel variant leads to the skipping of exon 8, which induces the loss of 24 native amino acids, resulting in a shortened COL4A2 protein (p.Pro161_Gly184del). CONCLUSION: Our study demonstrated that c.549 + 5G > A in COL4A2 gene is a disease-causing variant by aberrant splicing. This finding enriches the variant spectrum of COL4A2 gene, which not only improves the understanding of the fetal neurological disorders associated with hypoxic-ischemic and hemorrhagic lesions from a clinical perspective but also provides guidance on genetic diagnosis and counseling.