RASA1 Research Articles

Unusual case of Parkes-Weber syndrome in a patient with spontaneous subarachnoid hemorrhage

Introduction. Parkes-Weber syndrome (PWS) is a complex and rare genetic disease of combined vascular malformations that primarily occur in the extremities and can involve the pelvic blood vessels. In extremely rare cases, the disease is manifested by endocranial and spinal involvement. The treatment of such patients represents a challenge for neurosurgical centers and requires a multidisciplinary approach. Case report. We present the case of a 46-year-old male patient admitted to the emergency department due to spontaneous subarachnoid hemorrhage (SAH), moderate flaccid paraparesis, and urinary incontinence. The patient was previously diagnosed with PWS, while the genetic evaluation proved the RASA1 gene mutation. Furthermore, he experienced a spontaneous SAH and was hospitalized 26 years ago, while six years ago, he underwent a right nephrectomy due to multiple hilar aneurysms of the right renal artery and its branches. Digital subtraction angiography of the endocranium was performed, which detected no aneurysmal dilatations or arteriovenous malformations (AVM). The magnetic resonance imaging recorded spinal intradural AVM in the vertebral levels between T12 and L3, which completely filled the dural sac. After the conservative treatment, there was a significant improvement in the patient?s neurological and clinical condition. Conclusion. To the best of our knowledge, this is the only case report of a patient with PWS who had a spinal intradural AVM and spontaneous SAH without high-output heart failure and with a history of a previous nephrectomy.

Evaluation of NF1 and RASA1 gene expression in endometriosis.

BackgroundEndometrios affecting 6–10% of women of reproductive ages around the globe. Important pathways, including the MAPK and PI3K / Akt pathways, have been identified in the disease. The NF1 and RASA1 genes inactivate Ras by their own GTPase activity and controlled the high activity of these pathways.ObjectiveIn this study, we measured NF1 and RASA1 gene expression in the endometrial tissues of patients (eutopic and ectopic tissues) compared to the control samples.Materials and methodsIn our study, tissue samples were collected from 15 patients with endometriosis and 15 healthy women. We used quantitative polymerase chain reaction (qRT-PCR) to measure the NF1 and RASA1 gene expression levels in these samples.ResultsWe observed a significant decrease in the expression level of the NF1 gene in both eutopic and ectopic samples of endometriosis patients compared to control samples, while the expression of the RASA1 gene was significantly reduced only in ectopic tissues.

Arteriovenous Cerebral High Flow Shunts in Children: From Genotype to Phenotype.

ObjectiveTo study the genotypes and phenotypes of cerebral arteriovenous fistulas that drain or do not drain through the vein of Galen, and true vein of Galen aneurysmal malformations, in order to determine whether genotyping could help improve classification of these malformations and their management.MethodsWe carried out a retrospective review of genetic and phenotypic data in databases of four centers. All children with cerebral arteriovenous fistula or vein of Galen aneurysmal malformations aged below 18 years at onset were included. We recorded the nature of the genetic variant or absence of variant, age at onset, type of malformation, symptoms at onset (hemorrhage, neurological deficit, hydrocephalus, incidental, and heart failure), type of venous drainage and the long-term outcome.ResultsOne hundred and fifteen children were included. Autosomal dominant variants were identified in 39% of patients. The most frequent variant affected was the RASA1 gene (25%) followed by EPHB4 (8%) and the HHT-associated genes (5%). HHT gene variants were only observed in pial arteriovenous fistula not draining into the vein of Galen; on the contrary, EPHB4 variants were only seen in genuine vein of Galen aneurysmal malformation. RASA1 variants were identified in all types of shunts.ConclusionsEPHB4 variants seem specific to the vein of Galen aneurysmal malformation, RASA1 variants are associated with either pial arteriovenous fistulas or with genuine VGAM and HHT gene variants seem specific to pial arteriovenous fistulas. The genetic data helps to classify these malformations and to guide treatment toward lowest risk of post-operative cerebral ischemic-hemorrhagic complications.

Mutational spectrum of syndromic genes in sporadic brain arteriovenous malformation

BackgroundBrain arteriovenous malformations (BAVMs) are abnormal vessels that are apt to rupture, causing life-threatening intracranial hemorrhage (ICH). The estimated prevalence of BAVMs is 0.05% among otherwise healthy individuals. In this study, we aim to investigate the mutational spectrum of syndromic genes in sporadic BAVM.MethodsWe recruited a cohort of 150 patients with BAVM and performed whole-exome sequencing on their peripheral blood DNA. To explore the mutational spectrum of syndromic genes in sporadic brain arteriovenous malformation, we selected six genes according to the Online Mendelian Inheritance in Man (OMIM) and literature. All variants in the six candidate genes were extracted and underwent filtering for qualifying variants.ResultsThere are a total of four patients with rare variants in hereditary hemorrhagic telangiectasia-related genes. In addition, we identified two patients have the variant of RASA1 gene in our database, which are also rare mutations that are absent from population databases. However, we did not find any patients with GNAQ mutations in our database. ConclusionsIn conclusion, we demonstrated that variants in syndromic vascular malformations play important roles in the etiology of sporadic BAVM.

Cyanosis in a Previously Well Child.

Cyanosis in a Previously Well Child.

Abnormal H3K27 histone methylation of RASA1 gene leads to unexplained recurrent spontaneous abortion by regulating Ras-MAPK pathway in trophoblast cells.

Some studies suggest that the inactivation of the Ras-MAPK pathway in trophoblast cells can lead to recurrent abortion, but the molecular mechanism underlying the inactivation of this pathway in trophoblast cells is still unclear. This study aimed to explore the relationship between the mechanism of abnormal activation of RASA1, a regulatory protein of the Ras-MAPK pathway, and unexplained recurrent spontaneous abortion. RT-qPCR was used to detect the transcription levels of RASA1 gene. Immunohistochemistry and Western blot were used to detect the expression levels of the RASA1, Raf and MEK proteins. CCK-8, TUNEL and Transwell assays were used to detect the proliferative, apoptotic, and invasive capacities of HTR-8/SVneo cells. ChIP assays were used to detect the enrichment of H3K27me3 in RASA1 gene promoter. Abortion villi experiments showed that the enrichment of H3K27me3 in the RASA1 gene promoter was reduced, and that both RASA1 gene transcription and RASA1 protein expression were increased. Cell experiments confirmed that RASA1 could decrease the phosphorylated Raf and MEK proteins, inhibit the proliferation and invasion ability, and promote the apoptosis ability of HTR-8/SVneo cells. It was also found that the proliferation and invasion ability as well as the Ras-MAPK pathway activity of HTR-8/SVneo cells were inhibited when treated with histone methyltransferase inhibitor DZNep. RASA1 gene was abnormally activated in unexplained recurrent spontaneous abortion villi due to the decreased enrichment of H3K27me3 in the gene promoter. High expression of RASA1 could inhibit the activity of the Ras-MAPK pathway, and thus inhibit the proliferation and invasion ability of trophoblast cells.

Congenital Chylothorax and Hydrops Fetalis: A Novel Neonatal Presentation of RASA1 Mutation

Mutations in the RASA1 gene are known to cause arteriovenous malformations (AVMs), with evidence of associated lymphatic malformations. We report for the first time, to the best of our knowledge, an infant with RASA1 mutation presenting with hydrops fetalis and chylothorax, but without an associated AVM. Previously, researchers studying rodents have found chylothorax associated with RASA1 mutations, and, in previous case reports, researchers have reported on infants with RASA1 mutations born with hydrops fetalis and AVMs. In this report, we describe the case of a "late preterm" female infant born with nonimmune hydrops fetalis and congenital chylothorax who was detected to have a RASA1 deletion on genetic workup. Although classically described phenotypes of RASA1 mutations present with venous malformations, no such malformations were found in this infant on extensive imaging. This combination is a novel and nonclassic presentation of RASA1 mutation. In cases of congenital chylothorax, especially with nonimmune hydrops fetalis, RASA1 mutations should be considered as part of the differential diagnosis and genetic testing should be included as part of a complete workup to allow for screening for associated vascular anomalies.

A Neonatal Case with a Prenatal Diagnosis of Capillary Malformation-arteriovenous Malformation Syndrome (CM-AVM)

Capillary malformation arteriovenous malformation syndrome (CV-AVM) is marked by the appearance of vascular lesions on the skin, frequently found on the face and limbs. The main genetic defect in this syndrome is a mutation in the RASA-1 gene transmitted in an autosomal dominant manner. Besides, this syndrome is characterized by a wide intra- and interfamilial variability in clinical manifestations. In fact, little is known about prenatally diagnosed cases of CV-AVM. Here, we report the case of a 25 year-old woman admitted during her third pregnancy for management of unexplained polyhydramnios. Prenatal genetic analysis (Mendeliom sequencing from amniotic fluid), performed due to two previous unexplained fetal losses, showed a mutation in a heterozygous state in RASA-1 gene c.2367 C>T (p.Arg789*). Hence, an antenatal diagnosis of CV AVM was then made. An emergency cesarean section was performed at 31 5/7 weeks due to complications of the second amnioreduction. At birth, the neonate presented five erythematous lesions with diameters of 1-3 cm, similarly to those found on the father. No signs of arteriovenous malformations was detected on MRI of the brain and spine. No other anomaly has been found. Despite its autosomal mode of transmission, CV-AVM is still underrecognized due to its variable clinical presentation. Our report underlines that CM-AVM should be considered at the first clinical examination of a neonate revealing atypical capillary malformations especially in the context of unexplained polyhydramnios, previous fetal losses, or family history of clinical presentation of CM. When genetic diagnose is made a follow-up should be organized during the period of early childhood.

Role of colour-Doppler high-frequency ultrasonography in capillary malformation-arteriovenous malformation syndrome: a case series.

High-frequency ultrasonography (HFUS) represents a useful adjunct for dermatologists in the diagnosis of capillary malformation-arteriovenous malformation (CM-AVM) syndrome. We present a paediatric case series of 6 patients with confirmed RASA1 gene mutation in whom HFUS demonstrated AVM beneath cutaneous CM-like lesions greater than 1.5cm.

Identification of a novel frameshift mutation in the Rasa1 gene associated with capillary malformation-arteriovenous malformation syndrome: Case report

Identification of a novel frameshift mutation in the Rasa1 gene associated with capillary malformation-arteriovenous malformation syndrome: Case report

RASA1-dependent cellular export of collagen IV controls blood and lymphatic vascular development.

Combined germline and somatic second hit inactivating mutations of the RASA1 gene, which encodes a negative regulator of the Ras signaling pathway, cause blood and lymphatic vascular lesions in the human autosomal dominant vascular disorder capillary malformation-arteriovenous malformation (CM-AVM). How RASA1 mutations in endothelial cells (EC) result in vascular lesions in CM-AVM is unknown. Here, using different murine models of RASA1-deficiency, we found that RASA1 was essential for the survival of EC during developmental angiogenesis in which primitive vascular plexuses are remodeled into hierarchical vascular networks. RASA1 was required for EC survival during developmental angiogenesis because it was necessary for export of collagen IV from EC and deposition in vascular basement membranes. In the absence of RASA1, dysregulated Ras mitogen-activated protein kinase (MAPK) signal transduction in EC resulted in impaired folding of collagen IV and its retention in the endoplasmic reticulum (ER) leading to EC death. Remarkably, the chemical chaperone, 4-phenylbutyric acid, and small molecule inhibitors of MAPK and 2-oxoglutarate dependent collagen IV modifying enzymes rescued ER retention of collagen IV and EC apoptosis and resulted in normal developmental angiogenesis. These findings have important implications with regards an understanding of the molecular pathogenesis of CM-AVM and possible means of treatment.

Mutational signatures and the genomic landscape of betel quid chewing-associated tongue carcinoma.

Our study presents the genetic landscape betel quid chewing‐associated tongue carcinomas (BQ‐TCs). We compared the genetic landscape and mutational signatures of 15 BQ‐TCs, five nonbetel quid chewing‐associated tongue carcinomas (nBQ‐TCs), and 82 tongue carcinomas in general population from the TCGA (TCGA‐TCs) project. The highlights of this research mainly include: (a) The genetic landscape of BQ‐TC was characterized with frequent mutations in RASA1 gene and in CpG islands throughout the genome. (b) The BQ‐TC had a distinct mutational signature from that of nBQ‐TC and tongue carcinomas in the general population, and this signature was associated with the mutations in RASA1 and in CpG islands. (c) Our study indicates that betel quid (BQ) chewing classifies a distinct group of tongue carcinoma. The BQ chewing might not contribute to the tumorigenesis of tongue carcinomas as a mutagen.

Expanding the clinical and molecular findings in RASA1 capillary malformation-arteriovenous malformation.

RASA1-related disorders are vascular malformation syndromes characterized by hereditary capillary malformations (CM) with or without arteriovenous malformations (AVM), arteriovenous fistulas (AVF), or Parkes Weber syndrome. The number of cases reported is relatively small; and while the main clinical features are CMs and AVMs/AVFs, the broader phenotypic spectrum caused by variants in the RASA1 gene is still being defined. Here, we report the clinical and molecular findings in 69 unrelated cases with a RASA1 variant identified at ARUP Laboratories. Sanger sequencing and multiplex ligation-dependent probe amplification were primarily used to evaluate RASA1. Several atypical cases were evaluated using next-generation sequencing (NGS) and array-comparative genomic hybridization (aCGH). Sixty individuals had a deleterious RASA1 variant of which 29 were novel. Nine individuals had a variant of uncertain significance. Five large RASA1 deletions were detected, giving an overall deletion/duplication rate of 8.3% (5/60) among positive cases. Most (75.4%) individuals with a RASA1 variant had CMs, and 44.9% had an AVM/AVF. Clinical findings in several cases expand the RASA1 phenotype. Our data suggest that screening for large RASA1 deletions and duplications in this disorder is important and suggest that NGS multi-gene panel testing is beneficial for the molecular diagnosis of cases with complex vascular phenotypes.

Somatic second hit mutation of RASA1 in vascular endothelial cells in capillary malformation-arteriovenous malformation

Capillary malformation-arteriovenous malformation (CM-AVM) is an autosomal dominant vascular disorder that is associated with inherited inactivating mutations of the RASA1 gene in the majority of cases. Characteristically, patients exhibit one or more focal cutaneous CM that may occur alone or together with AVM, arteriovenous fistulas or lymphatic vessel abnormalities. The focal nature and varying presentation of lesions has led to the hypothesis that somatic “second hit” inactivating mutations of RASA1 are necessary for disease development. In this study, we examined CM from four different CM-AVM patients for the presence of somatically acquired RASA1 mutations. All four patients were shown to possess inactivating heterozygous germline RASA1 mutations. In one of the patients, a somatic inactivating RASA1 mutation (c.1534C > T, p.Arg512*) was additionally identified in CM lesion tissue. The somatic RASA1 mutation was detected within endothelial cells specifically and was in trans with the germline RASA1 mutation. Together with the germline RASA1 mutation (c.2125C > T, p.Arg709*) in the same patient, the endothelial cell somatic RASA1 mutation likely contributed to lesion development. These studies provide the first clear evidence of the second hit model of CM-AVM pathogenesis.

Concomitant Unusual Presentation of an Arteriovenous Malformation in a Mother and Child

Arterio-venous malformations (AVMs) are rare vascular anomalies due to the absent interposition of the capillary system between arteries and veins. Despite many AVMs being asymptomatic, pain, bleeding, functional impairment, and neurological compression can be observed, depending on the location of the lesion. Surgical removal of symptomatic lesions is the gold standard treatment. The vast majority of AVMs are sporadic, with only few familial cases reported. The pathogenics of the lesions are still elusive, although mutations in the PTEN and RASA1 gene have been identified. We report on an unusual presentation of an AVM occurring in similar anatomic locations and within concurring time spans, in a daughter and her mother. Both patients were negative for the known mutations.

RASA1 regulates the function of lymphatic vessel valves in mice.

Capillary malformation-arteriovenous malformation (CM-AVM) is a blood and lymphatic vessel (LV) disorder that is caused by inherited inactivating mutations of the RASA1 gene, which encodes p120 RasGAP (RASA1), a negative regulator of the Ras small GTP-binding protein. How RASA1 mutations lead to the LV leakage defects that occur in CM-AVM is not understood. Here, we report that disruption of the Rasa1 gene in adult mice resulted in loss of LV endothelial cells (LECs) specifically from the leaflets of intraluminal valves in collecting LVs. As a result, valves were unable to prevent fluid backflow and the vessels were ineffective pumps. Furthermore, disruption of Rasa1 in midgestation resulted in LEC apoptosis in developing LV valves and consequently failed LV valvulogenesis. Similar phenotypes were observed in induced RASA1-deficient adult mice and embryos expressing a catalytically inactive RASA1R780Q mutation. Thus, RASA1 catalytic activity is essential for the function and development of LV valves. These data provide a partial explanation for LV leakage defects and potentially other LV abnormalities observed in CM-AVM.

Impairment of PI3K/AKT and WNT/β-catenin pathways in bone marrow mesenchymal stem cells isolated from patients with myelodysplastic syndromes

Bone marrow mesenchymal stem cells (BM-MSCs) exhibit multiple abnormalities in myelodysplastic syndromes (MDS), including impaired proliferative and clonogenic capacity, altered morphology, increased senescence, impaired immunoregulatory properties, and reduced hematopoietic support capacity. Common signaling pathways, such as PI3K/AKT and WNT/β-catenin, regulate multiple MSC properties, including proliferation, differentiation, and cell-cell interaction. Here, with polymerase chain reaction arrays, we investigated the expression of 84 genes belonging to the PI3K/AKT signaling pathways in BM-MSCs isolated from patients with MDS, acute myeloid leukemia, and therapy-related myeloid neoplasms, using as a control BM-MSCs isolated from patients with untreated early-stage lymphomas without BM involvement. Statistically significant downregulation of GSK3β, SOS1, RASA1, and MTCP1 gene expression was observed in BM-MSCs isolated from patients with de novo MDS, as compared with controls. Moreover, expression of the GSK3β protein was reduced in MDS-derived MSCs, and was associated with concomitant reduction of phosphorylation at Ser-9. The role of GSK3β in the downstream WNT/β-catenin signaling pathway was assessed. We investigated β-catenin protein levels and expression of 84 genes belonging to the WNT target gene pathway using PCR arrays in MDS BM-MSCs, as compared with control BM-MSCs. GSK3β impairment translated into decreased β-catenin protein levels and downregulation of several WNT/β-catenin target genes (SOX9, EGR1, WISP1). These findings suggest that deregulation of genes involved in the PI3K/AKT and WNT signaling pathways may contribute to the phenotypical abnormalities of MDS BM-MSCs.

Fetal MRI demonstrating vein of Galen malformations in two successive pregnancies--a previously unreported occurrence.

Vein of Galen malformations are rare and are usually detected in utero using ultrasonography. No definite genetic predisposition has been described in the literature. We present a case with two successive pregnancies complicated by vein of Galen malformations, which were assessed using fetal MRI. The putative role of genetic mutations is also discussed. A 30-year-old primigravida presented in the third trimester with a fetus diagnosed with vein of Galen malformation on sonography. MRI and MR angiography were performed for further assessment. The subsequent pregnancy was again complicated by vein of Galen malformation. In addition to MRI, genetic analysis was carried out on both fetuses and on the parents. MR angiography revealed that both fetuses suffered from the choroidal sub-type of vein of Galen malformation, with multiple arterial feeders fistulating onto a midline venous pouch. The visualised anatomy obtained was far superior than on sonography and allowed categorisation of vein of Galen malformation sub-type. Genetic analysis on the mother and both fetuses showed variant RASA1 gene mutation. This case demonstrates that fetal MRI is a powerful tool in the investigation of in utero neurovascular malformations. A genetic mutation was identified, but this was of uncertain significance.

31 DEREGULATION OF PI3K/AKT SIGNALING AND WNT TARGET GENES IN BONE MARROW MESENCHYMAL STROMAL CELLS FROM PATIENTS WITH MDS

Bone marrow mesenchymal stem cells (BM-MSCs) exhibit multiple abnormalities in myelodysplastic syndromes (MDS), including impaired proliferative and clonogenic capacity, altered morphology, increased senescence, impaired immunoregulatory properties, and reduced hematopoietic support capacity. Common signaling pathways, such as PI3K/AKT and WNT/β-catenin, regulate multiple MSC properties, including proliferation, differentiation, and cell–cell interaction. Here, with polymerase chain reaction arrays, we investigated the expression of 84 genes belonging to the PI3K/AKT signaling pathways in BM-MSCs isolated from patients with MDS, acute myeloid leukemia, and therapy-related myeloid neoplasms, using as a control BM-MSCs isolated from patients with untreated early-stage lymphomas without BM involvement. Statistically significant downregulation of GSK3β, SOS1, RASA1, and MTCP1 gene expression was observed in BM-MSCs isolated from patients with de novo MDS, as compared with controls. Moreover, expression of the GSK3β protein was reduced in MDS-derived MSCs, and was associated with concomitant reduction of phosphorylation at Ser-9. The role of GSK3β in the downstream WNT/β-catenin signaling pathway was assessed. We investigated β-catenin protein levels and expression of 84 genes belonging to the WNT target gene pathway using PCR arrays in MDS BM-MSCs, as compared with control BM-MSCs. GSK3β impairment translated into decreased β-catenin protein levels and downregulation of several WNT/β-catenin target genes (SOX9, EGR1, WISP1). These findings suggest that deregulation of genes involved in the PI3K/AKT and WNT signaling pathways may contribute to the phenotypical abnormalities of MDS BM-MSCs.

Hypotrichosis associated with capillary malformation-arteriovenous malformation syndrome.

Capillary malformation-arteriovenous malformation (CM-AVM) syndrome is associated with multifocal small CMs and a high risk for high-flow lesions. It is an autosomal dominant disorder, caused by RASA1 gene mutations. Recently, two novel clinical features have been identified: numerous small pale halos with central punctate red spots, and naevus anemicus. To identify the prevalence of the new clinical manifestations in our patients with CM-AVM. The secondary objective was to investigate the presence of other skin lesions. We retrospectively searched the picture database of our department for cases with a clinical diagnosis of CM-AVM, based on the identification of multiple cutaneous CMs and a negative history of epistaxis. We prospectively conducted a clinical and dermoscopic skin examination in all of these patients. Seven patients with multiple CMs were found, and only in one case was a cutaneous AVM present. Five patients had red punctate spots surrounded by pale halos on the upper limbs. Two adult patients also showed multiple telangiectasias on the neck and upper trunk. Naevus anemicus was not detected in any patient. A partial or total absence of vellous hair on the surface of CMs was observed in all patients. Red punctate spots with pale halos or small telangiectasias are frequent findings in CM-AVM syndrome. Hypotrichosis on the CMs suggests that RASA1 gene mutations could be involved in the hair follicle proliferation and cell cycle.