ABSTRACT
Primary lymphedema (PL), characterized by tissue swelling, fat accumulation, and fibrosis, results from defects in lymphatic vessels or valves caused by mutations in genes involved in development, maturation, and function of the lymphatic vascular system. Pathogenic variants in various genes have been identified in about 30% of PL cases. By screening of a cohort of 755 individuals with PL, we identified two TIE1 (tyrosine kinase with immunoglobulin- and epidermal growth factor-like domains 1) missense variants and one truncating variant, all predicted to be pathogenic by bioinformatic algorithms. The TIE1 receptor, in complex with TIE2, binds angiopoietins to regulate the formation and remodeling of blood and lymphatic vessels. The premature stop codon mutant encoded an inactive truncated extracellular TIE1 fragment with decreased mRNA stability, and the amino acid substitutions led to decreased TIE1 signaling activity. By reproducing the two missense variants in mouse Tie1 via CRISPR/Cas9, we showed that both cause edema and are lethal in homozygous mice. Thus, our results indicate that TIE1 loss-of-function variants can cause lymphatic dysfunction in patients. Together with our earlier demonstration that ANGPT2 loss-of-function mutations can also cause PL, our results emphasize the important role of the ANGPT2/TIE1 pathway in lymphatic function.
Subject(s)
Loss of Function Mutation , Lymphedema , Receptor, TIE-1 , Lymphedema/genetics , Lymphedema/pathology , Lymphedema/metabolism , Humans , Animals , Mice , Receptor, TIE-1/genetics , Receptor, TIE-1/metabolism , Female , Male , Mutation, Missense , Age of Onset , Middle Aged , Adult , Receptor, TIE-2ABSTRACT
BACKGROUND: Vascular anomalies caused by somatic (postzygotic) variants are clinically and genetically heterogeneous diseases with overlapping or distinct entities. The genetic knowledge in this field is rapidly growing, and genetic testing is now part of the diagnostic workup alongside the clinical, radiological and histopathological data. Nonetheless, access to genetic testing is still limited, and there is significant heterogeneity across the approaches used by the diagnostic laboratories, with direct consequences on test sensitivity and accuracy. The clinical utility of genetic testing is expected to increase progressively with improved theragnostics, which will be based on information about the efficacy and safety of the emerging drugs and future molecules. The aim of this study was to make recommendations for optimising and guiding the diagnostic genetic testing for somatic variants in patients with vascular malformations. RESULTS: Physicians and lab specialists from 11 multidisciplinary European centres for vascular anomalies reviewed the genes identified to date as being involved in non-hereditary vascular malformations, evaluated gene-disease associations, and made recommendations about the technical aspects for identification of low-level mosaicism and variant interpretation. A core list of 24 genes were selected based on the current practices in the participating laboratories, the ISSVA classification and the literature. In total 45 gene-phenotype associations were evaluated: 16 were considered definitive, 16 strong, 3 moderate, 7 limited and 3 with no evidence. CONCLUSIONS: This work provides a detailed evidence-based view of the gene-disease associations in the field of vascular malformations caused by somatic variants. Knowing both the gene-phenotype relationships and the strength of the associations greatly help laboratories in data interpretation and eventually in the clinical diagnosis. This study reflects the state of knowledge as of mid-2023 and will be regularly updated on the VASCERN-VASCA website (VASCERN-VASCA, https://vascern.eu/groupe/vascular-anomalies/ ).
Subject(s)
Genetic Testing , Vascular Malformations , Humans , Genetic Testing/methods , Vascular Malformations/genetics , Vascular Malformations/diagnosis , Vascular Malformations/pathology , Genetic Association StudiesABSTRACT
Repurposing anticancer drugs to vascular malformations has significantly improved patient outcomes. Complex Lymphatic Anomalies (CLA) are part of the spectrum of lymphatic malformations (LMs) that share similar oncogenic mutations to cancer. We report the case of a young patient with highly symptomatic CLA who was initially treated with sirolimus, due to the frequent involvement of the PI3K-AKT-mTOR pathway in CLA pathogenesis. Despite an initial reduction in symptoms, sirolimus progressively lost its effectiveness. After an unsuccessful attempt with trametinib alone, sirolimus was added to trametinib and resulted in a significant, rapid and sustained improvement in symptoms. This suggests that, contrary to current dogmas, combination therapy using sub-therapeutic doses targeting both the PI3K and RAS pathways retains efficacy without generating the toxicity known for combination therapies, and is beneficial in the management of CLAs and potentially other vascular anomalies.
Subject(s)
Lymphatic Abnormalities , Pyridones , Pyrimidinones , Sirolimus , Humans , Lymphatic Abnormalities/drug therapy , Lymphatic Abnormalities/pathology , Pyridones/therapeutic use , Pyrimidinones/therapeutic use , Sirolimus/therapeutic useABSTRACT
Background: Venous malformations (VMs) are commonly associated with localized intravascular coagulopathy leading to elevated D-dimer and risks of hemorrhagic and thromboembolic events, particularly in extensive lesions. While low-molecular-weight heparin (LMWH) has been effective in managing coagulopathy and pain, direct oral anticoagulants (DOACs) emerge as a promising alternative. Objectives: This study aims to evaluate the efficacy and safety of DOACs in treating VMs associated with localized intravascular coagulopathy, offering a comparative perspective to LMWH. Methods: A retrospective study was conducted on 29 patients with VMs and secondary localized intravascular coagulopathy treated with DOACs between 2013 and 2023 in a single tertiary center specialized in vascular anomalies. Data were collected from February 24, 2023, to September 1, 2023. Results: Patients' median age was 40 years (range, 22-76 years), with a female predominance of 66%. Descriptive statistical analysis showed that 85% of patients experienced pain improvement, and 86% showed a reduction in D-dimer by at least 25%, with a mean reduction of 57% (SD, ±32%; IQR, [38-81%]). Additionally, 37% of patients reported a bleeding event, mostly minor. Conclusion: The study findings suggests that DOACs may serve as an alternative to LMWH for patients with VMs associated with pain management and reduced D-dimer, alongside a low observed risk of major bleeding. Tailored dosing considering the location of the malformation, bleeding and thrombotic tendencies, and laboratory abnormalities is recommended. Future studies with larger cohorts and extended follow-up are necessary for more conclusive evidence on DOACs' role in this patient population.
ABSTRACT
Developmental and functional defects in the lymphatic system are responsible for primary lymphoedema (PL). PL is a chronic debilitating disease caused by increased accumulation of interstitial fluid, predisposing to inflammation, infections and fibrosis. There is no cure, only symptomatic treatment is available. Thirty-two genes or loci have been linked to PL, and another 22 are suggested, including Hepatocyte Growth Factor (HGF). We searched for HGF variants in 770 index patients from the Brussels PL cohort. We identified ten variants predicted to cause HGF loss-of-function (six nonsense, two frameshifts, and two splice-site changes; 1.3% of our cohort), and 14 missense variants predicted to be pathogenic in 17 families (2.21%). We studied co-segregation within families, mRNA stability for non-sense variants, and in vitro functional effects of the missense variants. Analyses of the mRNA of patient cells revealed degradation of the nonsense mutant allele. Reduced protein secretion was detected for nine of the 14 missense variants expressed in COS-7 cells. Stimulation of lymphatic endothelial cells with these 14 HGF variant proteins resulted in decreased activation of the downstream targets AKT and ERK1/2 for three of them. Clinically, HGF-associated PL was diverse, but predominantly bilateral in the lower limbs with onset varying from early childhood to adulthood. Finally, aggregation study in a second independent cohort underscored that rare likely pathogenic variants in HGF explain about 2% of PL. Therefore, HGF signalling seems crucial for lymphatic development and/or maintenance in human beings and HGF should be included in diagnostic genetic screens for PL.
Subject(s)
Hepatocyte Growth Factor , Lymphedema , Humans , Hepatocyte Growth Factor/genetics , Hepatocyte Growth Factor/metabolism , Male , Female , Child , Adult , Lymphedema/genetics , Lymphedema/pathology , Adolescent , Middle Aged , Animals , Mutation, Missense/genetics , Loss of Function Mutation , Age of Onset , Child, Preschool , COS Cells , Chlorocebus aethiops , Endothelial Cells/metabolism , Endothelial Cells/pathology , Young AdultABSTRACT
Pathogenic loss-of-function variants in BGN, an X-linked gene encoding biglycan, are associated with Meester-Loeys syndrome (MRLS), a thoracic aortic aneurysm/dissection syndrome. Since the initial publication of five probands in 2017, we have considerably expanded our MRLS cohort to a total of 18 probands (16 males and 2 females). Segregation analyses identified 36 additional BGN variant-harboring family members (9 males and 27 females). The identified BGN variants were shown to lead to loss-of-function by cDNA and Western Blot analyses of skin fibroblasts or were strongly predicted to lead to loss-of-function based on the nature of the variant. No (likely) pathogenic missense variants without additional (predicted) splice effects were identified. Interestingly, a male proband with a deletion spanning the coding sequence of BGN and the 5' untranslated region of the downstream gene (ATP2B3) presented with a more severe skeletal phenotype. This may possibly be explained by expressional activation of the downstream ATPase ATP2B3 (normally repressed in skin fibroblasts) driven by the remnant BGN promotor. This study highlights that aneurysms and dissections in MRLS extend beyond the thoracic aorta, affecting the entire arterial tree, and cardiovascular symptoms may coincide with non-specific connective tissue features. Furthermore, the clinical presentation is more severe and penetrant in males compared to females. Extensive analysis at RNA, cDNA, and/or protein level is recommended to prove a loss-of-function effect before determining the pathogenicity of identified BGN missense and non-canonical splice variants. In conclusion, distinct mechanisms may underlie the wide phenotypic spectrum of MRLS patients carrying loss-of-function variants in BGN.
ABSTRACT
Capillary malformations (CMs) are the most common type of vascular anomalies, affecting around 0.3% of newborns. They are usually caused by somatic pathogenic variants in GNAQ or GNA11. PIK3CA and PIK3R1, part of the phosphoinositide 3-kinase-protein kinase B-mammalian target of rapamycin pathway, are mutated in fainter CMs such as diffuse CM with overgrowth and megalencephaly CM. In this study, we present two young patients with a CM-like phenotype associated with cerebral anomalies and severe epilepsy. Pathogenic variants in PIK3CA and PIK3R1, as well as GNAQ and GNA11, were absent in affected cutaneous tissue biopsies. Instead, we identified two somatic pathogenic variants in the AKT3 gene. Subsequent analysis of the DNA obtained from surgically resected brain tissue of one of the two patients confirmed the presence of the AKT3 variant. Focal cortical dysplasia was also detected in this patient. Genetic analysis thus facilitated workup to reach a precise diagnosis for these patients, associating the vascular anomaly with the neurological symptoms. This study underscores the importance of searching for additional signs and symptoms to guide the diagnostic workup, especially in cases with atypical vascular malformations. In addition, it strongly emphasizes the significance of genotype-phenotype correlation studies in guiding clinicians' informed decision-making regarding patient care.
Subject(s)
Capillaries , Epilepsy , Proto-Oncogene Proteins c-akt , Telangiectasis , Vascular Malformations , Female , Humans , Infant, Newborn , Male , Capillaries/abnormalities , Capillaries/pathology , Epilepsy/genetics , Epilepsy/pathology , Genetic Association Studies , Genetic Predisposition to Disease , Mosaicism , Mutation/genetics , Phenotype , Proto-Oncogene Proteins c-akt/genetics , Telangiectasis/genetics , Telangiectasis/pathology , Telangiectasis/diagnosis , Vascular Malformations/genetics , Vascular Malformations/pathology , Vascular Malformations/diagnosis , Vascular Malformations/complications , AdolescentABSTRACT
BACKGROUNDSlow-flow vascular malformations frequently harbor activating mutations in the PI3K/AKT/mTOR cascade. Phase II trials pinpointed sirolimus effectiveness as a drug therapy. Efficacy and safety of sirolimus thus need to be evaluated in large prospective phase III trials.METHODSThe Vascular Anomaly-Sirolimus-Europe (VASE) trial, initiated in 2016, is a large multicentric prospective phase III trial (EudraCT 2015-001703-32), which evaluates efficacy and safety of sirolimus for 2 years in pediatric and adult patients with symptomatic slow-flow vascular malformations. In this interim analysis, we studied all patients enrolled up to October 2021 who received sirolimus for 12 or more months or who prematurely stopped the treatment.RESULTSThirty-one pediatric and 101 adult patients were included in this analysis; 107 completed 12 or more months of sirolimus, including 61 who were treated for the whole 2-year period. Sirolimus resulted in a clinical improvement in 85% of patients. The efficacy appeared within the first month for the majority of them. Grade 3-4 adverse events were observed in 24 (18%) patients; all resolved after treatment interruption/arrest. Sirolimus increased feasibility of surgery or sclerotherapy in 20 (15%) patients initially deemed unsuitable for intervention. Among the 61 patients who completed the 2-year treatment, 33 (54%) reported a recurrence of symptoms after a median follow-up of 13 months after sirolimus arrest. While there was no difference in efficacy, clinical improvement was faster but subsided more rapidly in PIK3CA-mutated (n = 24) compared with TIE2-mutated (n = 19) patients.CONCLUSIONSirolimus has a high efficacy and good tolerance in treatment of slow-flow vascular malformations in children and adults.TRIAL REGISTRATIONClinicalTrials.gov NCT02638389 and EudraCT 2015-001703-32.FUNDINGThe Fonds de la Recherche Scientifique (FNRS grants T.0247.19, P.C005.22, T.0146.16, and P.C013.20), the Fund Generet managed by the King Baudouin Foundation (grant 2018-J1810250-211305), the Walloon Region through the FRFS-WELBIO strategic research programme (WELBIO-CR-2019C-06), the MSCA-ITN network V.A. Cure no. 814316, the Leducq Foundation Networks of Excellence Program grant "ReVAMP" (LFCR grant 21CVD03), the European Union's Horizon 2020 research and innovation programme under grant agreement no. 874708 (Theralymph), the Swiss National Science Foundation under the Sinergia project no. CRSII5_193694, and a Pierre M. fellowship.
Subject(s)
Sirolimus , Vascular Malformations , Adult , Child , Humans , Europe , Phosphatidylinositol 3-Kinases , Prospective Studies , Sirolimus/adverse effects , Vascular Malformations/drug therapy , Vascular Malformations/geneticsABSTRACT
BACKGROUND: Primary lymphoedema (PL) is a chronic, debilitating disease caused by developmental and functional defects of the lymphatic system. It is marked by an accumulation of interstitial fluid, fat and tissue fibrosis. There is no cure. More than 50 genes and genetic loci have been linked to PL. We sought to study systematically cell polarity signalling protein Cadherin Epidermal Growth Factor Laminin G Seven-pass G-type Receptor 1 (CELSR1) variants linked to PL. METHODS: We investigated 742 index patients from our PL cohort using exome sequencing. RESULTS: We identified nine variants predicted to cause CELSR1 loss of function. Four of them were tested for nonsense-mediated mRNA decay, but none was observed. Most of the truncated CELSR1 proteins would lack the transmembrane domain, if produced. The affected individuals had puberty/late-onset PL on lower extremities. The variants had a statistically significant difference in penetrance between female patients (87%) and male patients (20%). Eight variant carriers had a kidney anomaly, mostly in the form of ureteropelvic junction obstruction, which has not been associated with CELSR1 before. CELSR1 is located in the 22q13.3 deletion locus of the Phelan-McDermid syndrome. As variable renal defects are often seen in patients with the Phelan-McDermid syndrome, CELSR1 may be the long-sought gene for the renal defects. CONCLUSION: PL associated with a renal anomaly suggests a CELSR1-related cause.
Subject(s)
Chromosome Disorders , Lymphedema , Female , Humans , Male , Cadherins/genetics , Cadherins/metabolism , Chromosome Deletion , Chromosome Disorders/genetics , Lymphedema/geneticsABSTRACT
PURPOSE: The study aimed to clinically and molecularly characterize the neurodevelopmental disorder associated with heterozygous de novo variants in CNOT9. METHODS: Individuals were clinically examined. Variants were identified using exome or genome sequencing. These variants were evaluated using in silico predictions, and their functional relevance was further assessed by molecular models and research in the literature. The variants have been classified according to the criteria of the American College of Medical Genetics. RESULTS: We report on 7 individuals carrying de novo missense variants in CNOT9, p.(Arg46Gly), p.(Pro131Leu), and p.(Arg227His), and, recurrent in 4 unrelated individuals, p.(Arg292Trp). All affected persons have developmental delay/intellectual disability, with 5 of them showing seizures. Other symptoms include muscular hypotonia, facial dysmorphism, and behavioral abnormalities. Molecular modeling predicted that the variants are damaging and would lead to reduced protein stability or impaired recognition of interaction partners. Functional analyses in previous studies showed a pathogenic effect of p.(Pro131Leu) and p.(Arg227His). CONCLUSION: We propose CNOT9 as a novel gene for neurodevelopmental disorder and epilepsy.
Subject(s)
Epilepsy , Intellectual Disability , Neurodevelopmental Disorders , Humans , Epilepsy/genetics , Intellectual Disability/genetics , Intellectual Disability/pathology , Mutation, Missense/genetics , Neurodevelopmental Disorders/genetics , Neurodevelopmental Disorders/pathology , Phenotype , Seizures/geneticsABSTRACT
BACKGROUND: Congenital hydrocephalus is characterized by ventriculomegaly, defined as a dilatation of cerebral ventricles, and thought to be due to impaired cerebrospinal fluid (CSF) homeostasis. Primary congenital hydrocephalus is a subset of cases with prenatal onset and absence of another primary cause, e.g., brain hemorrhage. Published series report a Mendelian cause in only a minority of cases. In this study, we analyzed exome data of PCH patients in search of novel causal genes and addressed the possibility of an underlying oligogenic mode of inheritance for PCH. MATERIALS AND METHODS: We sequenced the exome in 28 unrelated probands with PCH, 12 of whom from families with at least two affected siblings and 9 of whom consanguineous, thereby increasing the contribution of genetic causes. Patient exome data were first analyzed for rare (MAF < 0.005) transmitted or de novo variants. Population stratification of unrelated PCH patients and controls was determined by principle component analysis, and outliers identified using Mahalanobis distance 5% as cutoff. Patient and control exome data for genes biologically related to cilia (SYScilia database) were analyzed by mutation burden test. RESULTS: In 18% of probands, we identify a causal (pathogenic or likely pathogenic) variant of a known hydrocephalus gene, including genes for postnatal, syndromic hydrocephalus, not previously reported in isolated PCH. In a further 11%, we identify mutations in novel candidate genes. Through mutation burden tests, we demonstrate a significant burden of genetic variants in genes coding for proteins of the primary cilium in PCH patients compared to controls. CONCLUSION: Our study confirms the low contribution of Mendelian mutations in PCH and reports PCH as a phenotypic presentation of some known genes known for syndromic, postnatal hydrocephalus. Furthermore, this study identifies novel Mendelian candidate genes, and provides evidence for oligogenic inheritance implicating primary cilia in PCH.
Subject(s)
Hydrocephalus , Multifactorial Inheritance , Female , Pregnancy , Humans , Mutation , Consanguinity , Databases, FactualABSTRACT
BACKGROUND: Cleidocranial dysplasia (CCD) is a rare skeletal dysplasia with significant clinical variability. Patients with CCD typically present with delayed closure of fontanels and cranial sutures, dental anomalies, clavicular hypoplasia or aplasia and short stature. Runt-related transcription factor 2 (RUNX2) is currently the only known disease-causing gene for CCD, but several studies have suggested locus heterogeneity. METHODS: The cohort consists of eight subjects from five unrelated families partially identified through GeneMatcher. Exome or genome sequencing was applied and in two subjects the effect of the variant was investigated at RNA level. RESULTS: In each subject a heterozygous pathogenic variant in CBFB was detected, whereas no genomic alteration involving RUNX2 was found. Three CBFB variants (one splice site alteration, one nonsense variant, one 2 bp duplication) were shown to result in a premature stop codon. A large intragenic deletion was found to delete exon 4, without affecting CBFB expression. The effect of a second splice site variant could not be determined but most likely results in a shortened or absent protein. Affected individuals showed similarities with RUNX2-related CCD, including dental and clavicular abnormalities. Normal stature and neurocognitive problems were however distinguishing features. CBFB encodes the core-binding factor ß subunit, which can interact with all RUNX proteins (RUNX1, RUNX2, RUNX3) to form heterodimeric transcription factors. This may explain the phenotypic differences between CBFB-related and RUNX2-related CCD. CONCLUSION: We confirm the previously suggested locus heterogeneity for CCD by identifying five pathogenic variants in CBFB in a cohort of eight individuals with clinical and radiographic features reminiscent of CCD.
Subject(s)
Cleidocranial Dysplasia , Core Binding Factor beta Subunit , Humans , Base Sequence , Cleidocranial Dysplasia/genetics , Cleidocranial Dysplasia/pathology , Codon, Nonsense , Core Binding Factor Alpha 1 Subunit/genetics , Core Binding Factor beta Subunit/genetics , ExonsABSTRACT
Sirolimus, by targeting the mammalian target of rapamycin (mTOR) pathway, has demonstrated efficacy on lymphatic malformations (LMs) in adults and neonates. The current hypothesis is that the earlier the lesion is treated, the better it responds. This has prompted the idea that sirolimus administration might be efficacious to treat fetal LMs as well. Here we report a successful management of a cervicofacial fetal LM with sirolimus taken orally by the mother from the 22nd week of pregnancy until 2 weeks before planned delivery. Repeated cordocentesis recorded a 30% transplacental crossing of sirolimus. Continuation of sirolimus after birth allowed resection of the residual mass. We have followed the physical and neurological evolution of the child for 6 years since the fetal administration of sirolimus. We conclude that early administration of sirolimus during pregnancy with maternal serum monitoring may be proposed to high-risk fetal LMs in selected cases.
Subject(s)
Sirolimus , Humans , Sirolimus/therapeutic use , Sirolimus/administration & dosage , Female , Pregnancy , Treatment Outcome , Lymphatic Abnormalities/drug therapy , Adult , Administration, Oral , Infant, Newborn , Ultrasonography, Prenatal , Cordocentesis , MTOR Inhibitors/therapeutic use , Gestational Age , Maternal-Fetal ExchangeABSTRACT
BACKGROUND AND PURPOSE: Sturge-Weber syndrome (SWS) is a neurocutaneous disorder characterized by clinical manifestations involving the brain, eye and skin. SWS is commonly caused by somatic mutations in G protein subunit Alpha Q (GNAQ). Five cases of subunit Alpha 11 (GNA11) mutations have been reported. We studied phenotypic features of GNA11-SWS and compared them with those of classic SWS. METHODS: Within two European multidisciplinary centers we looked for patients with clinical characteristics of SWS and a GNA11 mutation. Clinical and radiological data were collected retrospectively and prospectively. RESULTS: We identified three patients with SWS associated with a somatic GNA11 mutation. All had disseminated capillary malformation (CM) and hyper- or hypotrophy of an extremity. At birth, the CMs of the face, trunk and limbs were pink and patchy, and slowly darkened with age, evolving to a purple color. Two of the patients had glaucoma. All had neurological symptoms and moderate brain atrophy with a lower degree of severity than that classically associated with SWS. Susceptibility-weighted imaging (SWI) and contrast-enhanced fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging demonstrated the best sensitivity to reveal the pial angiomas. CONCLUSIONS: We have differentiated two distinct clinical/radiological phenotypes of SWS; GNAQ- and GNA11-SWS. The classic GNAQ-SWS is characterized by a homogeneous dark-red CM, commonly associated with underlying soft tissue hypertrophy. The CM in GNA11-SWS is more reticulate and darkens with time, and the neurological picture is milder. SWI and post-contrast FLAIR sequences appear to be necessary to demonstrate leptomeningeal angiomatosis. Anti-epileptic medication or future targeted therapies may be useful, as in classic SWS.
Subject(s)
GTP-Binding Protein alpha Subunits , Sturge-Weber Syndrome , Anticonvulsants , Brain/diagnostic imaging , Brain/pathology , GTP-Binding Protein alpha Subunits/genetics , Humans , Magnetic Resonance Imaging , Retrospective Studies , Sturge-Weber Syndrome/complications , Sturge-Weber Syndrome/genetics , Sturge-Weber Syndrome/pathologyABSTRACT
Objective: To 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. Methods: We 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. Results: One 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. Conclusions: EPHB4 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.
ABSTRACT
BACKGROUND: Venous malformations (VMs) are the most common vascular anomalies and have been associated with somatic variants in TEK. Current treatment of VM joint component might be challenging due to the size or location of some lesions or ineffective with recurrence of malformed veins. Targeted molecular therapies after identification of genetic defects might be an alternative. METHODS: We report a case with intraarticular bleeding due to VM with a TEK pathogenic somatic variant treated with rapamycin. RESULTS: A 26-year-old female patient was evaluated for right calf pain secondary to venous malformation of the right inferior limb with an intraarticular component in the right knee. Hemarthrosis and degenerative chondropathy of the knee were evidenced at MRA. Molecular diagnosis evidenced a pathogenic somatic TEK variant. Rapamycin was introduced to stop bleeding, with good tolerance and efficacy. CONCLUSION: The TEK receptor signals through the PI3K/AKT/mTOR pathway and TEK mutations have been linked to AKT activation. As rapamycin acts against angiogenesis and reduces phosphorylated-AKT levels, targeted molecular therapy should be discussed as first-line therapy in patients with proven molecular diagnosis and diffuse VM inaccessible to conventional treatment.
Subject(s)
Vascular Diseases , Vascular Malformations , Adult , Female , Hemarthrosis/drug therapy , Hemarthrosis/genetics , Humans , Phosphatidylinositol 3-Kinases/genetics , Proto-Oncogene Proteins c-akt , Sirolimus/therapeutic use , Vascular Malformations/complications , Vascular Malformations/drug therapy , Vascular Malformations/geneticsABSTRACT
Central conducting lymphatic anomaly (CCLA), characterized by the dysfunction of core collecting lymphatic vessels including the thoracic duct and cisterna chyli, and presenting as chylothorax, pleural effusions, chylous ascites, and lymphedema, is a severe disorder often resulting in fetal or perinatal demise. Although pathogenic variants in RAS/mitogen activated protein kinase (MAPK) signaling pathway components have been documented in some patients with CCLA, the genetic etiology of the disorder remains uncharacterized in most cases. Here, we identified biallelic pathogenic variants in MDFIC, encoding the MyoD family inhibitor domain containing protein, in seven individuals with CCLA from six independent families. Clinical manifestations of affected fetuses and children included nonimmune hydrops fetalis (NIHF), pleural and pericardial effusions, and lymphedema. Generation of a mouse model of human MDFIC truncation variants revealed that homozygous mutant mice died perinatally exhibiting chylothorax. The lymphatic vasculature of homozygous Mdfic mutant mice was profoundly mispatterned and exhibited major defects in lymphatic vessel valve development. Mechanistically, we determined that MDFIC controls collective cell migration, an important early event during the formation of lymphatic vessel valves, by regulating integrin ß1 activation and the interaction between lymphatic endothelial cells and their surrounding extracellular matrix. Our work identifies MDFIC variants underlying human lymphatic disease and reveals a crucial, previously unrecognized role for MDFIC in the lymphatic vasculature. Ultimately, understanding the genetic and mechanistic basis of CCLA will facilitate the development and implementation of new therapeutic approaches to effectively treat this complex disease.
Subject(s)
Chylothorax , Lymphatic Vessels , Lymphedema , Myogenic Regulatory Factors , Animals , Chylothorax/genetics , Chylothorax/metabolism , Endothelial Cells , Female , Humans , Hydrops Fetalis/genetics , Hydrops Fetalis/metabolism , Lymphatic Vessels/pathology , Lymphedema/genetics , Lymphedema/metabolism , Mice , Myogenic Regulatory Factors/genetics , PregnancyABSTRACT
Chromatin is essentially an array of nucleosomes, each of which consists of the DNA double-stranded fiber wrapped around a histone octamer. This organization supports cellular processes such as DNA replication, DNA transcription, and DNA repair in all eukaryotes. Human histone H4 is encoded by fourteen canonical histone H4 genes, all differing at the nucleotide level but encoding an invariant protein. Here, we present a cohort of 29 subjects with de novo missense variants in six H4 genes (H4C3, H4C4, H4C5, H4C6, H4C9, and H4C11) identified by whole-exome sequencing and matchmaking. All individuals present with neurodevelopmental features of intellectual disability and motor and/or gross developmental delay, while non-neurological features are more variable. Ten amino acids are affected, six recurrently, and are all located within the H4 core or C-terminal tail. These variants cluster to specific regions of the core H4 globular domain, where protein-protein interactions occur with either other histone subunits or histone chaperones. Functional consequences of the identified variants were evaluated in zebrafish embryos, which displayed abnormal general development, defective head organs, and reduced body axis length, providing compelling evidence for the causality of the reported disorder(s). While multiple developmental syndromes have been linked to chromatin-associated factors, missense-bearing histone variants (e.g., H3 oncohistones) are only recently emerging as a major cause of pathogenicity. Our findings establish a broader involvement of H4 variants in developmental syndromes.
Subject(s)
Histones , Zebrafish , Animals , Chromatin , DNA , Histones/metabolism , Humans , Syndrome , Zebrafish/genetics , Zebrafish/metabolismABSTRACT
Auriculocondylar syndrome (ACS) is a rare craniofacial disorder characterized by mandibular hypoplasia and an auricular defect at the junction between the lobe and helix, known as a "Question Mark Ear" (QME). Several additional features, originating from the first and second branchial arches and other tissues, have also been reported. ACS is genetically heterogeneous with autosomal dominant and recessive modes of inheritance. The mutations identified to date are presumed to dysregulate the endothelin 1 signaling pathway. Here we describe 14 novel cases and reassess 25 published cases of ACS through a questionnaire for systematic data collection. All patients harbor mutation(s) in PLCB4, GNAI3, or EDN1. This series of patients contributes to the characterization of additional features occasionally associated with ACS such as respiratory, costal, neurodevelopmental, and genital anomalies, and provides management and monitoring recommendations.
Subject(s)
Ear Diseases , Ear/abnormalities , Ear Diseases/genetics , Humans , Pedigree , PhenotypeABSTRACT
Importin 8, encoded by IPO8, is a ubiquitously expressed member of the importin-ß protein family that translocates cargo molecules such as proteins, RNAs, and ribonucleoprotein complexes into the nucleus in a RanGTP-dependent manner. Current knowledge of the cargoes of importin 8 is limited, but TGF-ß signaling components such as SMAD1-4 have been suggested to be among them. Here, we report that bi-allelic loss-of-function variants in IPO8 cause a syndromic form of thoracic aortic aneurysm (TAA) with clinical overlap with Loeys-Dietz and Shprintzen-Goldberg syndromes. Seven individuals from six unrelated families showed a consistent phenotype with early-onset TAA, motor developmental delay, connective tissue findings, and craniofacial dysmorphic features. A C57BL/6N Ipo8 knockout mouse model recapitulates TAA development from 8-12 weeks onward in both sexes but most prominently shows ascending aorta dilatation with a propensity for dissection in males. Compliance assays suggest augmented passive stiffness of the ascending aorta in male Ipo8-/- mice throughout life. Immunohistological investigation of mutant aortic walls reveals elastic fiber disorganization and fragmentation along with a signature of increased TGF-ß signaling, as evidenced by nuclear pSmad2 accumulation. RT-qPCR assays of the aortic wall in male Ipo8-/- mice demonstrate decreased Smad6/7 and increased Mmp2 and Ccn2 (Ctgf) expression, reinforcing a role for dysregulation of the TGF-ß signaling pathway in TAA development. Because importin 8 is the most downstream TGF-ß-related effector implicated in TAA pathogenesis so far, it offers opportunities for future mechanistic studies and represents a candidate drug target for TAA.