Genotypes and phenotypes of 162 families with a glomulin mutation

Glomovenous malformation secondary to a heterozygous nonsense variant in GLMN: a clinical mimicker of blue rubber bleb naevus syndrome

We present a case of multiple familial cutaneous venous malformations secondary to glomovenous malformation. This case illustrates the importance of considering alternative diagnoses, obtaining histology from venous lesions and genetic testing to help guide optimal management in cases of familial multiple cutaneous venous malformations.

Genetic mutations and phenotype characteristics in peripheral vascular malformations: A systematic review

Vascular malformations (VMs) are clinically diverse with regard to the vessel type, anatomical location, tissue involvement and size. Consequently, symptoms and disease impact differ significantly. Diverse causative mutations in more and more genes are discovered and play a major role in the development of VMs. However, the relationship between the underlying causative mutations and the highly variable phenotype of VMs is not yet fully understood. In this systematic review, we aimed to provide an overview of known causative mutations in genes in VMs and discuss associations between the causative mutations and clinical phenotypes. PubMed and EMBASE libraries were systematically searched on November 9th, 2022 for randomized controlled trials and observational studies reporting causative mutations in at least five patients with peripheral venous, lymphatic, arteriovenous and combined malformations. Study quality was assessed with the Newcastle-Ottawa Scale. Data were extracted on patient and VM characteristics, molecular sequencing method and results of molecular analysis. In total, 5667 articles were found of which 69 studies were included, reporting molecular analysis in a total of 4261 patients and 1686 (40%) patients with peripheral VMs a causative mutation was detected. In conclusion, this systematic review provides a comprehensive overview of causative germline and somatic mutations in various genes and associated phenotypes in peripheral VMs. With these findings, we attempt to better understand how the underlying causative mutations in various genes contribute to the highly variable clinical characteristics of VMs. Our study shows that some causative mutations lead to a uniform phenotype, while other causal variants lead to more varying phenotypes. By contrast, distinct causative mutations may lead to similar phenotypes and result in almost indistinguishable VMs. VMs are currently classified based on clinical and histopathology features, however, the findings of this systematic review suggest a larger role for genotype in current diagnostics and classification.

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/).

The Genetic Architecture of Vascular Anomalies: Current Data and Future Therapeutic Perspectives Correlated with Molecular Mechanisms

Vascular anomalies (VAs) are morphogenesis defects of the vascular system (arteries, capillaries, veins, lymphatic vessels) singularly or in complex combinations, sometimes with a severe impact on the quality of life. The progress made in recent years with the identification of the key molecular pathways (PI3K/AKT/mTOR and RAS/BRAF/MAPK/ERK) and the gene mutations that lead to the appearance of VAs has allowed the deciphering of their complex genetic architecture. Understanding these mechanisms is critical both for the correct definition of the phenotype and classification of VAs, as well as for the initiation of an optimal therapy and the development of new targeted therapies. The purpose of this review is to present in synthesis the current data related to the genetic factors involved in the etiology of VAs, as well as the possible directions for future research. We analyzed the data from the literature related to VAs, using databases (Google Scholar, PubMed, MEDLINE, OMIM, MedGen, Orphanet) and ClinicalTrials.gov. The obtained results revealed that the phenotypic variability of VAs is correlated with genetic heterogeneity. The identification of new genetic factors and the molecular mechanisms in which they intervene, will allow the development of modern therapies that act targeted as a personalized therapy. We emphasize the importance of the geneticist in the diagnosis and treatment of VAs, as part of a multidisciplinary team involved in the management of VAs.

How we approach genetics in the diagnosis and management of vascular anomalies

Vascular anomalies are a heterogeneous group of disorders that are currently classified based on their clinical and histological characteristics. Over the past decade, there have been significant advances in molecular genetics that have led to identification of genetic alterations associated with vascular tumors, vascular malformations, and syndromes. Here, we describe known genetic alterations in vascular anomalies, discuss when and how to test, and examine how identification of causative genetic mutations provides for better management of these disorders through improved understanding of their pathogenesis and increasing use of targeted therapeutic agents in order to achieve better outcomes for our patients.

Nosological and Theranostic Approach to Vascular Malformation through cfDNA NGS Liquid Biopsy

Several different nosological classifications have been used over time for vascular malformations (VMs) since clinical and pathological signs are largely overlapping. In a large proportion of cases, VMs are generated by somatic mosaicism in key genes, belonging to a few different molecular pathways. Therefore, molecular characterization may help in the understanding of the biological mechanisms related to the development of pathology. Tissue biopsy is not routinely included in the diagnostic path because of the need for fresh tissue specimens and the risk of bleeding. Bypassing the need for bioptic samples, we took advantage of the possibility of isolating cell-free DNA likely released by the affected tissues, to molecularly characterize 53 patients by cfDNA-NGS liquid biopsy. We found a good match between the identified variant and the clinical presentation. PIK3CA variants were found in 67% of Klippel Trenaunay Syndrome individuals; KRAS variants in 60% of arteriovenous malformations; MET was mutated in 75% of lymphovenous malformations. Our results demonstrate the power of cfDNA-NGS liquid biopsy in VMs clinical classification, diagnosis, and treatment. Indeed, tailored repurposing of pre-existing cancer drugs, such as PIK3CA, KRAS, and MET inhibitors, can be envisaged as adjuvant treatment, in addition to surgery and/or endovascular treatment, in the above-defined VMs categories, respectively.

GLMN causing vascular malformations: the clinical and genetic differentiation of cutaneous venous malformations

Cutaneous venous malformations frequently present with blue-pink lesions on the skin or mucosal surfaces. They can be problematic for patients who experience pain or unsightly lesions and can also be associated with significant bleeding. A proportion of venous malformations have been noted to occur in families, in particular glomuvenous malformations (GVMs). A 'two-hit' occurrence of genetic pathogenic variants appears to explain the appearance of GVMs, with the initial change in the germline copy of GLMN followed by a second somatic hit. Here we discuss a report of siblings experiencing such lesions, which were diagnosed as GVMs by genetic testing. We include a review of the literature regarding the clinical and genetic differences between these groups of venous malformations.

Venous Malformations in Childhood: Clinical, Histopathological and Genetics Update

Our knowledge in vascular anomalies has grown tremendously in the past decade with the identification of key molecular pathways and genetic mutations that drive the development of vascular tumors and vascular malformations. This has led us to better understand the pathogenesis of vascular lesions, refine their diagnosis and update their classification while also exploring the opportunity for a targeted molecular treatment. This paper aims to provide an overview of venous malformations (VM) in childhood. Specific entities include common VMs, cutaneo-mucosal VM, blue rubber bleb nevus syndrome or Bean syndrome, glomuvenous malformation, cerebral cavernous malformation, familial intraosseous vascular malformation and verrucous venous malformation. The clinicopathological features and the molecular basis of each entity are reviewed.

Clinical variability in multifocal lymphangioendotheliomatosis with thrombocytopenia: a review of the literature

Multifocal lymphangioendotheliomatosis with thrombocytopenia (MLT) is a recently recognized disorder characterized by vascular lesions marked by distinct endothelial proliferation. Lesions affect multiple tissues, and MLT can be associated with refractory thrombocytopenia resulting in life-threatening bleeding. Diagnosing MLT may be challenging given its rarity and phenotypic variability. There is no consensus on the optimal management or treatment duration. We report a 4-month-old male who presented with multiple vascular malformations involving the gastrointestinal tract, lung, bones, choroid plexus, and spleen, with minimal cutaneous involvement and no thrombocytopenia. Wedge resection of a pulmonary nodule was strongly positive for lymphatic vessel endothelial hyaluronan receptor 1 favoring MLT despite the lack of thrombocytopenia. The patient's clinical symptoms and vascular lesions improved on sirolimus therapy. We review the literature to highlight the clinical variability of MLT and discuss the diagnostic and therapeutic options for MLT.

Genetic syndromes with vascular malformations - update on molecular background and diagnostics

Vascular malformations are present in a great variety of congenital syndromes, either as the predominant or additional feature. They pose a major challenge to the clinician: due to significant phenotype overlap, a precise diagnosis is often difficult to obtain, some of the malformations carry a risk of life threatening complications and, for many entities, treatment is not well established. To facilitate their recognition and aid in differentiation, we present a selection of notable congenital disorders of vascular system development, distinguishing between the heritable germinal and sporadic somatic mutations as their causes. Clinical features, genetic background and comprehensible description of molecular mechanisms is provided for each entity.

Multiple Bluish Nodules in a 20-Year-Old Female with Similar Lesions in Her Father

Glomuvenous malformations are congenital, benign, vascular malformations classified as subtypes of glomus tumors with predominant blood vessels, usually present at birth or childhood with multiple, bluish, soft papules and nodules or plaque-like cutaneous lesions. Later present with pronounced segmental lesions, superimposed on the primary lesions, suggesting type 2 segmental mosaicism. We present a rare case of familial glomuvenous malformations, a healthy young female presented with multiple bluish papules since birth which later developed dissemination later in her adolescence. Moreover, her father also had similar skin lesions on his left lower back.

FKBP51 and FKBP12.6-Novel and tight interactors of Glomulin

The protein factor Glomulin (Glmn) is a regulator of the SCF (Skp1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex. Mutations of Glmn lead to glomuvenous malformations. Glmn has been reported to be associated with FK506-binding proteins (FKBP). Here we present in vitro binding analyses of the FKBP—Glmn interaction. Interestingly, the previously described interaction of Glmn and FKBP12 was found to be comparatively weak. Instead, the closely related FKBP12.6 and FKBP51 emerged as novel binding partners. We show different binding affinities of full length and truncated FKBP51 and FKBP52 mutants. Using FKBP51 as a model system, we show that two amino acids lining the FK506-binding site are essential for binding Glmn and that the FKBP51-Glmn interaction is blocked by FKBP ligands. This data suggest FKBP inhibition as a pharmacological approach to regulate Glmn and Glmn-controlled processes.

The Many Faces of FKBP51

The FK506-binding protein 51 (FKBP51) has emerged as a key regulator of endocrine stress responses in mammals and as a potential therapeutic target for stress-related disorders (depression, post-traumatic stress disorder), metabolic disorders (obesity and diabetes) and chronic pain. Recently, FKBP51 has been implicated in several cellular pathways and numerous interacting protein partners have been reported. However, no consensus on the underlying molecular mechanisms has yet emerged. Here, we review the protein interaction partners reported for FKBP51, the proposed pathways involved, their relevance to FKBP51’s physiological function(s), the interplay with other FKBPs, and implications for the development of FKBP51-directed drugs.

Interpretation of Genomic Sequencing Results in Healthy and Ill Newborns: Results from the BabySeq Project

Genomic sequencing provides many opportunities in newborn clinical care, but the challenges of interpreting and reporting newborn genomic sequencing (nGS) results need to be addressed for its broader and effective application. The BabySeq Project is a pilot randomized clinical trial that explores the medical, behavioral, and economic impacts of nGS in well newborns and those admitted to a neonatal intensive care unit (NICU). Here we present childhood-onset and actionable adult-onset disease risk, carrier status, and pharmacogenomics findings from nGS of 159 newborns in the BabySeq Project. nGS revealed a risk of childhood-onset disease in 15/159 (9.4%) newborns; none of the disease risks were anticipated based on the infants' known clinical or family histories. nGS also revealed actionable adult-onset disease risk in 3/85 (3.5%) newborns whose parents consented to receive this information. Carrier status for recessive diseases and pharmacogenomics variants were reported in 88% and 5% of newborns, respectively. Additional indication-based analyses were performed in 29/32 (91%) NICU newborns and 6/127 (5%) healthy newborns who later had presentations that prompted a diagnostic analysis. No variants that sufficiently explained the reason for the indications were identified; however, suspicious but uncertain results were reported in five newborns. Testing parental samples contributed to the interpretation and reporting of results in 13/159 (8%) newborns. Our results suggest that nGS can effectively detect risk and carrier status for a wide range of disorders that are not detectable by current newborn screening assays or predicted based on the infant's known clinical or family history, and the interpretation of results can substantially benefit from parental testing.

Glomus tumor: a comprehensive review of the clinical and histopathologic features with report of two intraoral cases

BACKGROUND

Glomus tumors are benign neoplasms that most commonly present in the subungual region. Their occurrence in the oral cavity is exceedingly rare. Here, we present 2 cases from the oral cavity, detail their clinical and histopathologic features, and review the literature for solitary cases involving the oral regions.

STUDY DESIGN

The English language literature was queried for cases of benign glomus tumors in/around the oral cavity. Additional citations were cross-referenced from the identified sources.

RESULTS

Thirty-one cases of solitary glomus tumor in the oral and paraoral regions have been described, including the present cases. Patient age ranged from 10 to 85 years, with an average age of 47 years. In 12 of the 31 cases, the tumors occurred in the lips, 5 in the palate, 4 in the tongue, 4 in the buccal mucosa, 3 in the gingiva, and 1 each in the parotid, pterygoid fossa, and oropharynx. Only 18 of these cases had accompanying immunohistochemical stains, with 14 expressing positivity for muscle cell markers.

CONCLUSIONS

Although glomus tumors have distinct histopathologic features, diagnostic confusion may exist with regard to extradigital locations. Detailed documentation and discussion of the clinical and histopathologic features of rare tumors like these are vital to understanding them.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Variant discovery in patients with Mendelian vascular anomalies by next-generation sequencing and their use in patient clinical management

OBJECTIVE

An accurate "molecular" diagnosis and classification of similar but distinct diseases is sometime challenging but often crucial for the definition of the appropriate patient medical management and treatment as well as for genetic counseling and risk assessment in families. The advent of next-generation sequencing (NGS), which analysed all known disease-associated genes in parallel in a cost- and time-effective manner, eased this process of disease definition and also for vascular anomalies that are a heterogeneous group of vascular tumors and congenital circulatory malformations and often characterized by overlapping phenotypes.

METHODS

We designed a NGS-based screening of the 25 currently most prevalent genes identified in patients with vascular anomalies with Mendelian inheritance and applied this panel to study the DNA of 150 patients affected with vascular anomalies for autosomal recessive and autosomal dominant variants and to analyse the paired blood and DNA from intralesional biopsy specimens in 17 patients for somatic unbalance. Results were confirmed with Sanger sequencing.

RESULTS

We identified 14 pathogenic variants in 13 of 150 patients. Eight variants were previously reported as a disease-causing variant, and six were new. In 55 additional probands we detected 75 variants with unknown significance. Moreover, a previously reported somatic variant was detected in five of 17 available tissue biopsy specimens.

CONCLUSIONS

Our results show that many genes can cause a wide variety of syndromic and nonsyndromic disorders, confirming that genetic testing by NGS is the approach of choice to diagnose heritable vascular anomalies, especially, but not only, when an intralesional biopsy specimen is available. The identification of the causative genes and the possibility of tracing somatic variants in tissues provide important information about etiology, patient clinical management, and treatment, and it could highlight otherwise unsuspected clinical situations.

Variable Somatic TIE2 Mutations in Half of Sporadic Venous Malformations

Venous malformations (VMs) are the most frequent vascular malformations referred to specialized vascular anomaly centers. A rare (1-2%) familial form, termed cutaneomucosal venous malformation (VMCM), is caused by gain-of-function mutations in TIE2. More recently, sporadic VMs, characterized by the presence of large unifocal lesions, were shown to be caused by somatic mutations in TIE2. These include a frequent L914F change, and a series of double mutations in cis. All of which cause ligand-independent receptor hyperphosphorylation in vitro. Here, we expanded our study to assess the range of mutations that cause sporadic VM. To test for somatic changes, we screened the entire coding region of TIE2 in cDNA from resected VMs by direct sequencing. We detected TIE2 mutations in 17/30 (56.7%) of the samples. In addition to previously detected mutations, we identified 7 novel somatic intracellular TIE2 mutations in sporadic VMs, including 3 that cause premature protein truncation.