A New Tool to Identify Pediatric Patients with Atypical Diabetes Associated with Gene Polymorphisms.

Background: Recent diabetes subclassifications have improved the differentiation between patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus despite several overlapping features, yet without considering genetic forms of diabetes. We sought to facilitate the identification of monogenic diabetes by creating a new tool that we validated in a pediatric maturity-onset diabetes of the young (MODY) cohort. Methods: We first created the DIAgnose MOnogenic DIAbetes (DIAMODIA) criteria based on the pre-existing, but incomplete, MODY calculator. This new score is composed of four strong and five weak criteria, with patients having to display at least one weak and one strong criterion. Results: The effectiveness of the DIAMODIA criteria was evaluated in two patient cohorts, the first consisting of patients with confirmed MODY diabetes (n=34) and the second of patients with T1DM (n=390). These DIAMODIA criteria successfully detected 100% of MODY patients. Multiple correspondence analysis performed on the MODY and T1DM cohorts enabled us to differentiate MODY patients from T1DM. The three most relevant variables to distinguish a MODY from T1DM profile were: lower insulin-dose adjusted A1c score ≤9, glycemic target-adjusted A1c score ≤4.5, and absence of three anti-islet cell autoantibodies. Conclusion: We validated the DIAMODIA criteria, as it effectively identified all monogenic diabetes patients (MODY cohort) and succeeded to differentiate T1DM from MODY patients. The creation of this new and effective tool is likely to facilitate the characterization and therapeutic management of patients with atypical diabetes, and promptly referring them for genetic testing which would markedly improve clinical care and counseling, as well.

Somatic Loss-of-Function PIK3R1 and Activating Non-hotspot PIK3CA Mutations Associated with Capillary Malformation with Dilated Veins (CMDV).

Common capillary malformations are red vascular skin lesions, most commonly associated with somatic activating GNAQ or GNA11 mutations. We focused on capillary malformations lacking such a mutation to identify previously unreported genetic causes. We used targeted next-generation sequencing on 82 lesions. Bioinformatic analysis allowed the identification of 9 somatic pathogenic variants in PIK3R1 and PIK3CA, encoding for the regulatory and catalytic subunits of phosphoinositide 3-kinase, respectively. Recharacterization of these lesions unraveled a common phenotype: a pale capillary malformation associated with visible dilated veins. Primary endothelial cells from 2 PIK3R1-mutated lesions were isolated, and PI3k-Akt-mTOR and RAS-RAF-MAPK signaling were assessed by western blot. This unveiled an abnormal increase in Akt phosphorylation, effectively reduced by PI3K pathway inhibitors, such as mTOR, Akt, and PIK3CA inhibitors. The effects of mutant PIK3R1 were further studied using zebrafish embryos. Endothelium-specific expression of PIK3R1 mutants resulted in abnormal development of the posterior capillary-venous plexus. In summary, capillary malformation associated with visible dilated veins emerges as a clinical entity associated with somatic pathogenic variants in PIK3R1 or PIK3CA (nonhotspot). Our findings suggest that the activated Akt signaling can be effectively reversed by PI3K pathway inhibitors. In addition, the proposed zebrafish model holds promise as a valuable tool for future drug screening aimed at developing patient-tailored treatments.

Epilepsy with faint capillary malformation or reticulated telangiectasia associated with mosaic AKT3 pathogenic variants.

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.

Rare variant association on unrelated individuals in case-control studies using aggregation tests: existing methods and current limitations.

Over the past years, progress made in next-generation sequencing technologies and bioinformatics have sparked a surge in association studies. Especially, genome-wide association studies (GWASs) have demonstrated their effectiveness in identifying disease associations with common genetic variants. Yet, rare variants can contribute to additional disease risk or trait heterogeneity. Because GWASs are underpowered for detecting association with such variants, numerous statistical methods have been recently proposed. Aggregation tests collapse multiple rare variants within a genetic region (e.g. gene, gene set, genomic loci) to test for association. An increasing number of studies using such methods successfully identified trait-associated rare variants and led to a better understanding of the underlying disease mechanism. In this review, we compare existing aggregation tests, their statistical features and scope of application, splitting them into the five classical classes: burden, adaptive burden, variance-component, omnibus and other. Finally, we describe some limitations of current aggregation tests, highlighting potential direction for further investigations.

Molecular investigation in individuals with orofacial clefts and microphthalmia-anophthalmia-coloboma spectrum.

This study describes genomic findings among individuals with both orofacial clefts (OC) and microphthalmia/anophthalmia/coloboma (MAC) recorded in the Brazilian Database on Craniofacial Anomalies (BDCA). Chromosomal microarray analysis (CMA) and Whole Exome Sequencing (WES) were performed in 17 individuals with OC-MAC. Clinical interpretation of molecular findings was based on data available at the BDCA and on re-examination. No copy number variants (CNVs) classified as likely pathogenic or pathogenic were detected by CMA. WES allowed a conclusive diagnosis in six individuals (35.29%), two of them with variants in the CHD7 gene, and the others with variants in the TFAP2A, POMT1, PTPN11, and TP63 genes with the following syndromes: CHARGE, CHD7-spectrum, Branchiooculofacial, POMT1-spectrum, LEOPARD, and ADULT. Variants of uncertain significance (VUS) possibly associated to the phenotypes were found in six other individuals. Among the individuals with VUSes, three individuals presented variants in genes associated to defects of cilia structure and/or function, including DYNC2H1, KIAA0586, WDR34, INTU, RPGRIP1L, KIF7, and LMNA. These results show that WES was the most effective molecular approach for OC-MAC in this cohort. This study also reinforces the genetic heterogeneity of OC-MAC, and the importance of genes related to ciliopathies in this phenotype.

Preliminary results of the European multicentric phase III trial regarding sirolimus in slow-flow vascular malformations.

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.

Excalibur: A new ensemble method based on an optimal combination of aggregation tests for rare-variant association testing for sequencing data.

The development of high-throughput next-generation sequencing technologies and large-scale genetic association studies produced numerous advances in the biostatistics field. Various aggregation tests, i.e. statistical methods that analyze associations of a trait with multiple markers within a genomic region, have produced a variety of novel discoveries. Notwithstanding their usefulness, there is no single test that fits all needs, each suffering from specific drawbacks. Selecting the right aggregation test, while considering an unknown underlying genetic model of the disease, remains an important challenge. Here we propose a new ensemble method, called Excalibur, based on an optimal combination of 36 aggregation tests created after an in-depth study of the limitations of each test and their impact on the quality of result. Our findings demonstrate the ability of our method to control type I error and illustrate that it offers the best average power across all scenarios. The proposed method allows for novel advances in Whole Exome/Genome sequencing association studies, able to handle a wide range of association models, providing researchers with an optimal aggregation analysis for the genetic regions of interest.

The VASCERN-VASCA Working Group Diagnostic and Management Pathways for Venous Malformations.

To elaborate expert consensus patient pathways to guide patients and physicians toward efficient diagnostics and management of patients with venous malformations. Methods: VASCERN-VASCA (https://vascern.eu/) is a European network of multidisciplinary centers for Vascular Anomalies. The Nominal Group Technique was used to establish the pathways. Two facilitators were identified: one to propose initial discussion points and draw the pathways, and another to chair the discussion. A dermatologist (AD) was chosen as first facilitator due to her specific clinical and research experience. The draft was subsequently discussed within VASCERN-VASCA monthly virtual meetings and annual face-to-face meetings. Results: The Pathway starts from the clinical suspicion of a venous type malformation (VM) and lists the clinical characteristics to look for to support this suspicion. Strategies for subsequent imaging and histopathology are suggested. These aim to inform on the diagnosis and to separate the patients into 4 subtypes: (1) sporadic single VMs or (2) multifocal, (3) familial, multifocal, and (4) combined and/or syndromic VMs. The management of each type is detailed in subsequent pages of the pathway, which are color coded to identify sections on (1) clinical evaluations, (2) investigations, (3) treatments, and (4) associated genes. Actions relevant to all types are marked in separate boxes, including when imaging is recommended. When definite diagnoses have been reached, the pathway also points toward disease-specific additional investigations and recommendations for follow up. Options for management are discussed for each subtype, including conservative and invasive treatments, as well as novel molecular therapies. Conclusion: The collaborative efforts of VASCERN-VASCA, a network of the 9 Expert Centers, has led to a consensus Diagnostic and Management Pathways for VMs to assist clinicians and patients. It also emphasizes the role of multidisciplinary expert centers in the management of VM patients. This pathway will become available on the VASCERN website (http://vascern.eu/).

Ureteropelvic junction obstruction with primary lymphoedema associated with CELSR1 variants.

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.

Clinical phenotype of adolescent and adult patients with extracranial vascular malformation.

OBJECTIVE: In recent years, genotypic characterization of congenital vascular malformations (CVMs) has gained attention; however, the spectrum of clinical phenotype remains difficult to attribute to a genetic cause and is rarely described in the adult population. The aim of this study is to describe a consecutive series of adolescent and adult patients in a tertiary center, where a multimodal phenotypic approach was used for diagnosis. METHODS: We analyzed clinical findings, imaging, and laboratory results at initial presentation, and set a diagnosis according to the International Society for the Study of Vascular Anomalies (ISSVA) classification for all consecutively registered patients older than 14 years of age who were referred to the Center for Vascular Malformations at the University Hospital of Bern between 2008 and 2021. RESULTS: A total of 457 patients were included for analysis (mean age, 35 years; females, 56%). Simple CVMs were the most common (n = 361; 79%), followed by CVMs associated with other anomalies (n = 70; 15%), and combined CVMs (n = 26; 6%). Venous malformations (n = 238) were the most common CVMs overall (52%), and the most common simple CVMs (66%). Pain was the most frequently reported symptom in all patients (simple, combined, and vascular malformation with other anomalies). Pain intensity was more pronounced in simple venous and arteriovenous malformations. Clinical problems were related to the type of CVM diagnosed, with bleeding and skin ulceration in arteriovenous malformations, localized intravascular coagulopathy in venous malformations, and infectious complications in lymphatic malformations. Limb length difference occurred more often in patients with CVMs associated with other anomalies as compared with simple or combined CVM (22.9 vs 2.3%; P < .001). Soft tissue overgrowth was seen in one-quarter of all patients independent of the ISSVA group. CONCLUSIONS: In our adult and adolescent population with peripheral vascular malformations, simple venous malformations predominated, with pain as the most common clinical symptom. In one-quarter of cases, patients with vascular malformations presented with associated anomalies on tissue growth. The differentiation of clinical presentation with or without accompanying growth abnormalities need to be added to the ISSVA classification. Phenotypic characterization considering vascular and non-vascular features remains the cornerstone of diagnosis in adult as well as pediatric patients.

SATB2-Associated Syndrome Due to a c.715C>T:p(Arg239*) Variant in Adulthood: Natural History and Literature Review.

SATB2-associated syndrome (SAS) is a rare condition, and it is characterized by severe developmental delay/intellectual disability, especially severe speech delay/or absence, craniofacial abnormalities, and behavioral problems. Most of the published reports are limited to children, with little information about the natural history of the disease and the possible novel signs and symptoms or behavioral changes in adulthood. We describe the management and follow-up of a 25-year-old male with SAS due to a de novo heterozygous nonsense variant SATB2:c.715C>T:p.(Arg239*) identified by whole-exome sequencing and review the literature. The case herein described contributes to a better characterization of the natural history of this genetic condition and in addition to the genotype-phenotype correlation of the SATB2:c.715C>T:p.(Arg239*) variant in SAS, highlights some particularities of its management.

Transcriptional drifts associated with environmental changes in endothelial cells.

Environmental cues, such as physical forces and heterotypic cell interactions play a critical role in cell function, yet their collective contributions to transcriptional changes are unclear. Focusing on human endothelial cells, we performed broad individual sample analysis to identify transcriptional drifts associated with environmental changes that were independent of genetic background. Global gene expression profiling by RNA sequencing and protein expression by liquid chromatography-mass spectrometry directed proteomics distinguished endothelial cells in vivo from genetically matched culture (in vitro) samples. Over 43% of the transcriptome was significantly changed by the in vitro environment. Subjecting cultured cells to long-term shear stress significantly rescued the expression of approximately 17% of genes. Inclusion of heterotypic interactions by co-culture of endothelial cells with smooth muscle cells normalized approximately 9% of the original in vivo signature. We also identified novel flow dependent genes, as well as genes that necessitate heterotypic cell interactions to mimic the in vivo transcriptome. Our findings highlight specific genes and pathways that rely on contextual information for adequate expression from those that are agnostic of such environmental cues.

Splenectomy improves erythrocyte functionality in spherocytosis based on septin abundance, but not maturation defects.

Splenectomy improves the clinical parameters of patients with hereditary spherocytosis, but its potential benefit to red blood cell (RBC) functionality and the mechanism behind this benefit remain largely overlooked. Here, we compared 7 nonsplenectomized and 13 splenectomized patients with mutations in the ß-spectrin or the ankyrin gene. We showed that hematological parameters, spherocyte abundance, osmotic fragility, intracellular calcium, and extracellular vesicle release were largely but not completely restored by splenectomy, whereas cryohemolysis was not. Affected RBCs exhibited decreases in ß-spectrin and/or ankyrin contents and slight alterations in spectrin membrane distribution, depending on the mutation. These modifications were found in both splenectomized and nonsplenectomized patients and poorly correlated with RBC functionality alteration, suggesting additional impairments. Accordingly, we found an increased abundance of septins, small guanosine triphosphate-binding cytoskeletal proteins. Septins-2, -7, and -8 but not -11 were less abundant upon splenectomy and correlated with the disease severity. Septin-2 membrane association was confirmed by immunolabeling. Except for cryohemolysis, all parameters of RBC morphology and functionality correlated with septin abundance. The increased septin content might result from RBC maturation defects, as evidenced by (1) the decreased protein 4.2 and Rh-associated glycoprotein content in all patient RBCs, (2) increased endoplasmic reticulum remnants and endocytosis proteins in nonsplenectomized patients, and (3) increased lysosomal and mitochondrial remnants in splenectomized patients. Our study paves the way for a better understanding of the involvement of septins in RBC membrane biophysical properties. In addition, the lack of restoration of septin-independent cryohemolysis by splenectomy may call into question its recommendation in specific cases.

Seven cases of hereditary haemorrhagic telangiectasia-like hepatic vascular abnormalities associated with EPHB4 pathogenic variants.

BACKGROUND: EPHB4 loss of function is associated with type 2 capillary malformation-arteriovenous malformation syndrome, an autosomal dominant vascular disorder. The phenotype partially overlaps with hereditary haemorrhagic telangiectasia (HHT) due to epistaxis, telangiectases and cerebral arteriovenous malformations, but a similar liver involvement has never been described. METHODS: Members of the French HHT network reported their cases of EPHB4 mutation identified after an initial suspicion of HHT. Clinical, radiological and genetic characteristics were analysed. RESULTS: Among 21 patients with EPHB4, 15 had a liver imaging, including 7 with HHT-like abnormalities (2 female patients and 5 male patients, ages 43-69 years). Atypical epistaxis and telangiectases were noted in two cases each. They were significantly older than the eight patients with normal imaging (median: 51 vs 20 years, p<0.0006).The main hepatic artery was dilated in all the cases (diameter: 8-11 mm). Six patients had hepatic telangiectases. All kind of shunts were described (arteriosystemic: five patients, arterioportal: two patients, portosystemic: three patients). The overall liver appearance was considered as typical of HHT in six cases.Six EPHB4 variants were classified as pathogenic and one as likely pathogenic, with no specific hot spot. CONCLUSION: EPHB4 loss-of-function variants can be associated with HHT-like hepatic abnormalities and should be tested for atypical HHT presentations.

Biallelic ANGPT2 loss-of-function causes severe early-onset non-immune hydrops fetalis.

BACKGROUND: Hydrops fetalis, a pathological fluid accumulation in two or more body compartments, is aetiologically heterogeneous. We investigated a consanguineous family with recurrent pregnancy loss due to severe early-onset non-immune hydrops fetalis. METHODS AND RESULTS: Whole exome sequencing in four fetuses with hydrops fetalis revealed that they were homozygous for the angiopoietin-2 (ANGPT2) variant Chr8 (GRCh37/Hg19): 6385085T>C, NM_001147.2:c.557A>G. The substitution introduces a cryptic, exonic splice site predicted to result in loss of 10 nucleotides with subsequent shift in reading frame, leading to a premature stop codon. RNA analysis in the heterozygous parents demonstrated loss of detectable mutant allele, indicative of loss-of-function via nonsense-mediated mRNA decay. Serum ANGPT2 levels were reduced in the parents. In a pregnancy with a healthy, heterozygous child, transiently increased fetal nuchal translucency was noted. CONCLUSION: Pathogenic heterozygous ANGPT2 missense variants were recently shown to cause autosomal dominant primary lymphoedema. ANGPT2 is a ligand of the TIE1-TIE2 (tyrosine kinase with immunoglobulin-like and epidermal growth factor-like domains 1 and 2) pathway. It is critical to the formation and remodelling of blood and lymphatic vessels and is involved in vessel maintenance. ANGPT2 knockout mice die from generalised lymphatic dysfunction. We show here that a homozygous pathogenic variant causes loss-of-function and results in severe early-onset hydrops fetalis. This is the first report of an autosomal recessive ANGPT2-related disorder in humans.

Trametinib as a promising therapeutic option in alleviating vascular defects in an endothelial KRAS-induced mouse model.

Somatic activating Kirsten rat sarcoma viral oncogene homologue (KRAS) mutations have been reported in patients with arteriovenous malformations. By producing LSL-Kras (G12D); Cdh5 (PAC)-CreERT2 [iEC-Kras (G12D*)] mice, we hoped to activate KRAS within vascular endothelial cells (ECs) to generate an arteriovenous malformation mouse model. Neonatal mice were treated daily with tamoxifen from postnatal (PN) days 1-3. Mortality and phenotypes varied amongst iEC-Kras (G12D*) pups, with only 31.5% surviving at PN14. Phenotypes (focal lesions, vessel dilations) developed in a consistent manner, although with unpredictable severity within multiple soft tissues (such as the brain, liver, heart and brain). Overall, iEC-Kras (G12D*) pups developed significantly larger vascular lumen areas compared with control littermates, beginning at PN8. We subsequently tested whether the MEK inhibitor trametinib could effectively alleviate lesion progression. At PN16, iEC-Kras (G12D*) pup survival improved to 76.9%, and average vessel sizes were closer to controls than in untreated and vehicle-treated mutants. In addition, trametinib treatment helped normalize iEC-Kras (G12D*) vessel morphology in PN14 brains. Thus, trametinib could act as an effective therapy for KRAS-induced vascular malformations in patients.

Toward reporting standards for the pathogenicity of variant combinations involved in multilocus/oligogenic diseases.

Although standards and guidelines for the interpretation of variants identified in genes that cause Mendelian disorders have been developed, this is not the case for more complex genetic models including variant combinations in multiple genes. During a large curation process conducted on 318 research articles presenting oligogenic variant combinations, we encountered several recurring issues concerning their proper reporting and pathogenicity assessment. These mainly concern the absence of strong evidence that refutes a monogenic model and the lack of a proper genetic and functional assessment of the joint effect of the involved variants. With the increasing accumulation of such cases, it has become essential to develop standards and guidelines on how these oligogenic/multilocus variant combinations should be interpreted, validated, and reported in order to provide high-quality data and supporting evidence to the scientific community.

The VASCERN-VASCA working group diagnostic and management pathways for lymphatic malformations.

Lymphatic malformations (LMs) are developmental defects of lymphatic vessels. LMs are histologically benign lesions, however, due to localization, size, and unexpected swelling, they may cause serious complications that threaten vital functions such as compression of the airways. A large swelling of the face or neck may also be disfiguring and thus constitute a psychological strain for patients and their families. LMs are also highly immunologically reactive, and are prone to recurrent infections and inflammation causing pain as well as chronic oozing wounds. The European Reference Network on Rare Multisystemic Vascular Diseases (VASCERN) is dedicated to gathering the best expertise in Europe. There are only few available guidelines on management and follow up of LMs, which commonly focus on very specific situations, such as head and neck LM (Zhou et al., 2011). It is still unclear, what constitutes an indication for treatment of LMs and how to follow up the patients. The Vascular Anomalies Working Group (VASCA-WG) of VASCERN decided to develop a diagnostic and management pathway for the management of LMs with a Nominal Group Technique (NGT), a well-established, structured, multistep, facilitated group meeting technique used to generate consensus statements. The pathway was drawn following 2 face-to-face meetings and multiple web meetings to facilitate discussion, and by mail to avoid the influence of most authoritative members. The VASCA-WG has produced this opinion statement reflecting strategies developed by experts and patient representatives on how to approach patients with lymphatic malformations in a practical manner; we present an algorithmic view of the results of our work.

GNA11-mutated Sturge-Weber syndrome has distinct neurological and dermatological features.

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.

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

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.