PIK3CA-Related Disorders: From Disease Mechanism to Evidence-Based Treatments.

Recent advances in genetic sequencing are transforming our approach to rare-disease care. Initially identified in cancer, gain-of-function mutations of the PIK3CA gene are also detected in malformation mosaic diseases categorized as PIK3CA-related disorders (PRDs). Over the past decade, new approaches have enabled researchers to elucidate the pathophysiology of PRDs and uncover novel therapeutic options. In just a few years, owing to vigorous global research efforts, PRDs have been transformed from incurable diseases to chronic disorders accessible to targeted therapy. However, new challenges for both medical practitioners and researchers have emerged. Areas of uncertainty remain in our comprehension of PRDs, especially regarding the relationship between genotype and phenotype, the mechanisms underlying mosaicism, and the processes involved in intercellular communication. As the clinical and biological landscape of PRDs is constantly evolving, this review aims to summarize current knowledge regarding PIK3CA and its role in nonmalignant human disease, from molecular mechanisms to evidence-based treatments.

Somatic mutations in arteriovenous malformations in hereditary hemorrhagic telangiectasia support a bi-allelic two-hit mutation mechanism of pathogenesis.

Hereditary hemorrhagic telangiectasia (HHT) is an inherited disorder of vascular malformations characterized by mucocutaneous telangiectases and arteriovenous malformations (AVMs) in internal organs. HHT is caused by inheritance of a loss of function mutation in one of three genes. Although individuals with HHT are haploinsufficient for one of these genes throughout their entire body, rather than exhibiting a systemic vascular phenotype, vascular malformations occur as focal lesions in discrete anatomic locations. The inconsistency between genotype and phenotype has provoked debate over whether haploinsufficiency or a different mechanism gives rise to the vascular malformations. We previously showed that HHT-associated skin telangiectases develop by a two-hit mutation mechanism in an HHT gene. However, somatic mutations were identified in only half of the telangiectases, raising the question whether a second-hit somatic mutation is a necessary (required) event in HHT pathogenesis. Here, we show that another mechanism for the second hit is loss of heterozygosity across the chromosome bearing the germline mutation. Secondly, we investigate the two-hit mutation mechanism for internal organ AVMs, the source of much of the morbidity of HHT. Here, we identified somatic molecular genetic events in eight liver telangiectases, including point mutations and a loss of heterozygosity event. We also identified somatic mutations in one pulmonary AVM and two brain AVMs, confirming that mucocutaneous and internal organ vascular malformations undergo the same molecular mechanisms. Together, these data argue that bi-allelic loss of function in an HHT gene is a required event in the pathogenesis of HHT-associated vascular malformations.

Congenital Vascular and Lymphatic Diseases.

Over the past several centuries, the integration of contemporary medical techniques and innovative technologies, like genetic sequencing, have played a pivotal role in enhancing our comprehension of congenital vascular and lymphatic disorders. Nonetheless, the uncommon and complex characteristics of these disorders, especially considering their formation during the intrauterine stage, present significant obstacles in diagnosis and treatment. Here, we review the intricacies of these congenital abnormalities, offering an in-depth examination of key diagnostic approaches, genetic factors, and therapeutic methods.

Somatic RIT1 delins in arteriovenous malformations hyperactivate RAS-MAPK signaling amenable to MEK inhibition.

Arteriovenous malformations (AVM) are benign vascular anomalies prone to pain, bleeding, and progressive growth. AVM are mainly caused by mosaic pathogenic variants of the RAS-MAPK pathway. However, a causative variant is not identified in all patients. Using ultra-deep sequencing, we identified novel somatic RIT1 delins variants in lesional tissue of three AVM patients. RIT1 encodes a RAS-like protein that can modulate RAS-MAPK signaling. We expressed RIT1 variants in HEK293T cells, which led to a strong increase in ERK1/2 phosphorylation. Endothelial-specific mosaic overexpression of RIT1 delins in zebrafish embryos induced AVM formation, highlighting their functional importance in vascular development. Both ERK1/2 hyperactivation in vitro and AVM formation in vivo could be suppressed by pharmacological MEK inhibition. Treatment with the MEK inhibitor trametinib led to a significant decrease in bleeding episodes and AVM size in one patient. Our findings implicate RIT1 in AVM formation and provide a rationale for clinical trials with targeted treatments.

GNAQ R183Q somatic mutation contributes to aberrant arteriovenous specification in Sturge-Weber syndrome through Notch signaling.

Episcleral vasculature malformation is a significant feature of Sturge-Weber syndrome (SWS) secondary glaucoma, the density and diameter of which are correlated with increased intraocular pressure. We previously reported that the GNAQ R183Q somatic mutation was located in the SWS episclera. However, the mechanism by which GNAQ R183Q leads to episcleral vascular malformation remains poorly understood. In this study, we investigated the correlation between GNAQ R183Q and episcleral vascular malformation via surgical specimens, human umbilical vein endothelial cells (HUVECs), and the HUVEC cell line EA.hy926. Our findings demonstrated a positive correlation between episcleral vessel diameter and the frequency of the GNAQ R183Q variant. Furthermore, the upregulation of genes from the Notch signaling pathway and abnormal coexpression of the arterial marker EphrinB2 and venous marker EphB4 were demonstrated in the scleral vasculature of SWS. Analysis of HUVECs overexpressing GNAQ R183Q in vitro confirmed the upregulation of Notch signaling and arterial markers. In addition, knocking down of Notch1 diminished the upregulation of arterial markers induced by GNAQ R183Q. Our findings strongly suggest that GNAQ R183Q leads to malformed episcleral vasculatures through Notch-induced aberrant arteriovenous specification. These insights into the molecular basis of episcleral vascular malformation will provide new pathways for the development of effective treatments for SWS secondary glaucoma.

Microcystic lymphatic malformations in Turner syndrome are due to somatic mosaicism of PIK3CA.

Turner syndrome (45,X) is caused by a complete or partial absence of a single X chromosome. Vascular malformations occur due to abnormal development of blood and/or lymphatic vessels. They arise from either somatic or germline pathogenic variants in the genes regulating growth and apoptosis of vascular channels. Aortic abnormalities are a common, known vascular anomaly of Turner syndrome. However, previous studies have described other vascular malformations as a rare feature of Turner syndrome and suggested that vascular abnormalities in individuals with Turner syndrome may be more generalized. In this study, we describe two individuals with co-occurrence of Turner syndrome and vascular malformations with a lymphatic component. In these individuals, genetic testing of the lesional tissue revealed a somatic pathogenic variant in PIK3CA-a known and common cause of lymphatic malformations. Based on this finding, we conclude that the vascular malformations presented here and likely those previously in the literature are not a rare part of the clinical spectrum of Turner syndrome, but rather a separate clinical entity that may or may not co-occur in individuals with Turner syndrome.

The importance of patient-specific resources for families dealing with prenatal rare diseases.

Rare diseases (RDs) are defined as diseases that affect a low number of the population. Prenatal diagnoses of RDs can add a lot of unique stress for parents. For example, parents who have prenatal diagnoses experience not only grief of expectation, but are forced to become patient advocates with incomplete information as their child is not yet born, and in many cases parents experience a lot of uncertainty. This typically involves seeking support groups and finding pre- and postnatal specialists all which come with mental and financial cost. Here we discuss the importance of targeted patient resources for parents to help alleviate some of their stress. Patient advocacy organizations can be incredibly useful for parents to navigate the complex healthcare system and help mitigate feelings of isolation, especially when parents can talk to others in a similar situation. We collaborated with a patient organization to create a prenatal parent support guide to address how parental needs such as mental well-being and practicing self-care can be met. We hope that resources such as these can help empower those with a pregnancy affected with a RD diagnosis.

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.

ELMO2 biallelic pathogenic variants in a patient with gingival hypertrophy and cherubism phenotype: Case report and molecular review.

Ramon syndrome (OMIM #266270) was first described in a patient with cherubism, gingival fibromatosis, epilepsy, intellectual disability, hypertrichosis, and stunted growth. In 2018, Mehawej et al. described a patient with Ramon syndrome in whom a homozygous variant in ELMO2 was identified, suggesting that this gene may be the causative for this syndrome. ELMO2 biallelic pathogenic variants were also described in patients with a primary intraosseous vascular malformation (PIVM; OMIM #606893). These patients presented gingival bleeding and cherubism phenotype. Herein, a patient with gingival hypertrophy, neurodevelopmental delay, and cherubism phenotype with a novel homozygous predicted loss-of-function (LOF) variant in the ELMO2 gene and family recurrence was reported. A surgical approach to treat gingival bleeding and mandible vascular malformation was also described. Furthermore, this study includes a comprehensive literature review of molecular data regarding the ELMO2 gene. All the variants, except one described in the ELMO2, were predicted as LOF, including our patient's variant. There is an overlapping between PIVM, also caused by LOF biallelic variants in the ELMO2 gene, and Ramon syndrome, which can suggest that they are not different entities. However, due to a limited number of cases described with molecular evaluation, it is hard to establish a genotype-phenotype correlation. Our study supports that LOF pathogenic biallelic variants in the ELMO2 gene cause a phenotype that has cherubism and gingival hypertrophy as main characteristics.

Hepatic manifestations of hereditary haemorrhagic telangiectasia.

Hereditary haemorrhagic telangiectasia is a genetic condition of abnormal blood vessel formation resulting from an imbalance of pro- and anti-angiogenic products of the transforming growth factor ß/bone morphogenetic protein signalling pathway which contributes to vascular remodelling and maintenance. Hepatic vascular malformations are common although less frequently symptomatic, but may result in high-output cardiac failure, portal hypertension and biliary ischaemia. Whilst the understanding of the genetic and cell signalling pathways that are the hallmark of hereditary haemorrhagic telangiectasia have been clarified, there remain challenges in therapy for these patients. Only patients with symptomatic hepatic vascular malformations require treatment, with most (63%) responding to first-line medical therapy. For non-responders, bevacizumab is effective in reducing cardiac output in those with heart failure secondary to hepatic vascular malformations as well as other manifestations of the disease. Although liver transplantation is the only curative option, optimal timing is critical. Novel anti-angiogenetic drugs and those that target aberrant cell signalling pathway are being explored.

NRASQ61R mutation drives elevated angiopoietin-2 expression in human endothelial cells and a genetic mouse model.

BACKGROUND: Angiopoietin-2 (Ang-2) is increased in the blood of patients with kaposiform lymphangiomatosis (KLA) and kaposiform hemangioendothelioma (KHE). While the genetic causes of KHE are not clear, a somatic activating NRASQ61R mutation has been found in the lesions of KLA patients. PROCEDURE: Our study tested the hypothesis that the NRASQ61R mutation drives elevated Ang-2 expression in endothelial cells. Ang-2 was measured in human endothelial progenitor cells (EPC) expressing NRASQ61R and a genetic mouse model with endothelial targeted NRASQ61R. To determine the signaling pathways driving Ang-2, NRASQ61R EPC were treated with signaling pathway inhibitors. RESULTS: Ang-2 levels were increased in EPC expressing NRASQ61R compared to NRASWT by Western blot analysis of cell lysates and ELISA of the cell culture media. Ang-2 levels were elevated in the blood of NRASQ61R mutant mice. NRASQ61R mutant mice also had reduced platelet counts and splenomegaly with hypervascular lesions, like some KLA patients. mTOR inhibitor rapamycin attenuated Ang-2 expression by NRASQ61R EPC. However, MEK1/2 inhibitor trametinib was more effective blocking increases in Ang-2. CONCLUSIONS: Our studies show that the NRASQ61R mutation in endothelial cells induces Ang-2 expression in vitro and in vivo. In cultured human endothelial cells, NRASQ61R drives elevated Ang-2 through MAP kinase and mTOR-dependent signaling pathways.

The critical role of neuroimaging in hemicrania continua: A systematic review and case series.

BACKGROUND: Hemicrania continua is a primary unilateral headache characterized by ipsilateral parasympathetic and sympathetic autonomic features. A key diagnostic criterion is its dramatic response to indomethacin treatment; however, various vascular or structural abnormalities have been reported to cause secondary hemicrania continua, presenting with clinical features similar to those of the primary headache presentation. OBJECTIVE: We reviewed the literature to compile secondary hemicrania continua cases, highlighting the importance of imaging during the evaluation. Additionally, we also contributed our three cases to the existing studies. METHODS: We conducted a review of articles from the PubMed and EMBASE databases that described reported cases of secondary hemicrania continua, covering the period from 1993 to 2021. Our review included detailed patient information, signs, and symptoms of hemicrania continua, as well as information on indomethacin usage and headache resolution (if pertinent). RESULTS: Secondary hemicrania continua can result from a remarkably diverse range of structural and vascular lesions, yet clinical reports on long-term follow-up are lacking. Notably, cases may exhibit a classical response to indomethacin, emphasizing the importance of neuroimaging in excluding secondary cases. Our search yielded 41 cases meeting our criteria. We excluded six cases that were not treated with indomethacin or were unresponsive to it. Additionally, we present three cases that highlight the necessity of neuroimaging in evaluating hemicrania continua, along with short- and long-term clinical outcomes following indomethacin and lesion-directed treatments. Case 1 presented with daily right-sided headaches and cranial autonomic symptoms. Her pain completely resolved with indomethacin use. Neuroimaging of the brain revealed a laterally directed saccular aneurysm of the right internal carotid artery. Case 2 presented with continuous left-sided unilateral headaches with superimposed exacerbations. She complained of left-sided photophobia with a dull sensation in the left ear. Her symptoms decreased after 2 weeks of indomethacin use. Neuroimaging of the head indicated a benign tumor with mass effect into the left lateral medulla and inferior cerebellar peduncle. Case 3 presented with a right side-locked headache with daily, severe superimposed exacerbations. She had photophobia in the right eye and a right-sided Horner's syndrome, along with tearing during her exacerbations. Neuroimaging of the brain revealed a pituitary tumor and her pain completely resolved with indomethacin. CONCLUSION: Hemicrania continua is a rare headache disorder that can be either primary or secondary. Importantly, response to indomethacin can still occur in secondary hemicrania continua. Thus, neuroimaging should be considered to rule out underlying structural etiology in all cases, regardless of their clinical responsiveness to indomethacin therapy.

Optical coherence tomography-measured blood vessel characteristics of port-wine birthmarks by depth: A cross-sectional study.

BACKGROUND: Port-Wine Birthmarks (PWB) are congenital capillary malformations requiring multiple treatments. Optical coherence tomography (OCT), a noninvasive imaging technique, characterizes vessels in cutaneous vascular lesions, including PWBs. OBJECTIVE: To assess variability in blood vessel characteristics within and between individual PWBs. METHODS: OCT was used to measure blood vessel density (%) and modal vessel diameter (micrometers) at increments of 0.05 mm from the skin surface to a depth of 0.50 mm at several adjacent spots of single PWBs in this cross-sectional study. Average ratios of vessel density and diameter in affected to control skin were obtained for each PWB by averaging data for all spots within a lesion. Statistical analysis was performed with a linear mixed effects model using SPSS software (IBM Corporation). RESULTS: There was great variability in vessel density and diameter within and between PWBs. Depths where average ratios of vessel density were consistently greater in affected to control skin were shallow, between 0.15 mm and 0.2 mm deep from the skin surface. LIMITATIONS: Small sample size and device's inability to measure diameters smaller than 20 micrometers. CONCLUSION: There is variability in vessel density and diameter within and between PWBs. Individualized treatment planning guided by OCT mapping should be studied further.

Surgical management of lobar cerebral cavernous malformations in children: a single-center experience.

PURPOSE: We aimed to determine the surgical indications and postoperative outcomes among pediatric patients with lobar cerebral cavernous malformations (CCMs). METHODS: We retrospectively reviewed pediatric patients operated on for lobar CCM between March 2010 and August 2021. Indications for surgery included (1) intracranial hemorrhage, (2) symptomatic superficially located lesion, and (3) asymptomatic CCM in non-eloquent area in case of strong parental preferences. Patients presenting with seizures were assessed using Engel Epilepsy Surgery Outcome Scale. RESULTS: Twenty-one patients were included. The predominant symptoms were seizures (57.1%), headaches (33.3%), and focal neurological deficits (23.8%). Patients were qualified for surgery due to symptomatic intracranial hemorrhage (47.6%), drug-resistant epilepsy (28.6%), and focal neurological deficits (9.5%). Three patients (14.3%) were asymptomatic. A gross total resection of CCM with the surrounding hemosiderin rim was achieved in all patients. The mean follow-up was 52 months. No patient experienced surgery-related complications. In all individuals with a preoperative first episode of seizures or focal neurological deficits, the symptoms subsided. All six patients with drug-resistant epilepsy improved to Engel classes I (67%) and II (33%). CONCLUSION: Surgical removal of symptomatic lobar CCMs in properly selected candidates remains a safe option. Parental preferences may be considered a sole qualifying criterion for asymptomatic lobar CCM excision.

Intramedullary spinal capillary hemangioma with secondary neurulation defect in children.

Intramedullary spinal capillary hemangioma is a rare occurrence in pediatric patients, and only limited cases have been reported. This study presents the first two cases of spinal capillary hemangioma co-present with retained medullary cord and one case of spinal capillary hemangioma with lumbosacral lipomatous malformation. Previous literature on ten patients with this pathology was reviewed. We speculated pathogenesis, imaging features, and histopathologic findings of the disease.

Patient characteristics and disease spectrum in a German vascular anomalies center.

BACKGROUND: Vascular malformations are rare diseases that should be treated in dedicated vascular anomaly centers (VAC). There is only a small amount of data on the diagnostic and therapeutic handling of these patients, before they are referred to a VAC. PURPOSE: To demonstrate the disease-specific patient characteristics in a German VAC, which are required to determine diagnostic and therapeutic steps. MATERIAL AND METHODS: In a retrospective study, all patients who were treated in the VAC from April 2014 until August 2021 were identified. In total, 593 patients were included in this study. RESULTS: Almost all patients had previously consulted a physician (591/593, 99.7%). A mean of two different physicians had been consulted (range 0-10). Patients with more complex, syndromal vascular malformations had significantly more previous appointments (P = 0.0018). In only 44% (261/593) of patients, the referral diagnosis was made correctly. Most patients had been previously treated for their vascular anomaly: pharmacotherapy (n = 130; 21.9%), compression garments (n = 141; 23.8%), surgical resection (n = 80; 17.3%) and sclerotherapy (n = 68; 11.5%). Fifty-two patients who had been falsely diagnosed had also received therapy prior to their referral to the VAC (8.8%). Most patients received an ultrasound examination in the VAC (n = 464; 78.2%). Most frequently, compression therapy was prescribed (n = 256; 43.2%), followed by sclerotherapy (n = 175, 29.5%) and pharmacotherapy (n = 55; 9.3%). CONCLUSION: Patients suffering from vascular anomalies often go through a complicated scheduling with numerous outpatient appointments and have a high risk of misdiagnosis and mistreatment prolonging the medical condition. Therefore, patients with vascular anomalies should be treated in a dedicated vascular anomaly center.

Neonatal nasal necrosis: Case series and brief review.

There is limited information available on pressure-related neonatal nasal injuries. We present three neonates born with erythema and purpura of the nasal tip that subsequently ulcerated, then evolved into a thick eschar. Each healed well with conservative management but left behind significant scarring. The sharp demarcation and location of the lesions were suggestive of hypoxic tissue damage akin to halo scalp ring alopecia. Further investigation is necessary to elucidate the etiology and optimal management of this condition.

Delayed ulceration following combination pulse dye laser and topical sirolimus treatment for port wine birthmarks: A case series.

Port wine birthmarks (PWB) are capillary vascular malformations within the papillary and reticular dermis, most commonly occurring on the head and neck and may darken and thicken with age. Pulsed dye laser (PDL) is the gold standard of treatment for PWB as it selectively targets involved vessels. Sirolimus is a macrolide antibiotic that selectively inhibits mammalian target of rapamycin, thereby suppressing the angiogenesis pathways that can be activated by PDL. Sirolimus and PDL may be used together to treat PWB. We present a case series describing three cases of delayed ulceration and systemic sirolimus absorption following combination therapy, highlighting a potential complication and patient safety concern.

Capillary malformations in a child caused by a novel HRAS mutation.

A 6-year-old boy with multiple capillary malformations of the port-wine birthmark (PWB) type on the right leg since birth presented with a varicose vein and segmental overgrowth of the affected leg. Genetic testing on affected skin confirmed the presence of a somatic novel pathogenic HRAS 30 bp in-frame duplication/insertion in the switch II domain. This case illustrates the phenotypic overlap of different genotypes and shows that somatic HRAS pathogenic variants, especially in-frame duplications/insertions, must be added to the list of the underlying causes in capillary malformations.

Segmental congenital vascular anomaly with atrophy, ulceration, and scarring (SeCVAUS): Case series and review of literature.

BACKGROUND: Next-generation sequencing has greatly increased our understanding of vascular birthmarks. Many port-wine birthmarks are due to somatic mutations in GNAQ/GNA11 exon 183, but other genomic causes have been identified. Most congenital hemangiomas are due to somatic mutations in GNAQ/GNA11 at exon 209. Although genomically distinct, clinical overlap of congenital hemangiomas and port-wine birthmarks has occasionally been described. OBJECTIVE: We report a case series of a unique segmentally distributed vascular anomaly with overlapping characteristics of port-wine birthmarks and congenital hemangiomas with other distinctive features including ulceration, atrophy, and scarring. METHODS: This was a multicenter study with retrospective identification of patients via a detailed review of medical records. We also reviewed previously published cases. RESULTS: The clinical, histological, radiological, and genomic characteristics of 19 new and 13 previously reported cases characterized by segmental distribution, sharply demarcated borders, with variable thickening are presented. All cases had central atrophy with or without episodic ulceration. Those with genomic studies (13 out of 32) had somatic activating missense mutations in GNA11 or GNAQ codon 209. CONCLUSIONS: We describe the features and propose a descriptive name segmental congenital vascular anomaly with atrophy, ulceration, and scarring (SeCVAUS) for this condition.