Biomarker Landscape in RASopathies.

RASopathies are a group of related genetic disorders caused by mutations in genes within the RAS/MAPK signaling pathway. This pathway is crucial for cell division, growth, and differentiation, and its disruption can lead to a variety of developmental and health issues. RASopathies present diverse clinical features and pose significant diagnostic and therapeutic challenges. Studying the landscape of biomarkers in RASopathies has the potential to improve both clinical practices and the understanding of these disorders. This review provides an overview of recent discoveries in RASopathy molecular profiling, which extend beyond traditional gene mutation analysis. mRNAs, non-coding RNAs, protein expression patterns, and post-translational modifications characteristic of RASopathy patients within pivotal signaling pathways such as the RAS/MAPK, PI3K/AKT/mTOR, and Rho/ROCK/LIMK2/cofilin pathways are summarized. Additionally, the field of metabolomics holds potential for uncovering metabolic signatures associated with specific RASopathies, which are crucial for developing precision medicine. Beyond molecular markers, we also examine the role of histological characteristics and non-invasive physiological assessments in identifying potential biomarkers, as they provide evidence of the disease's effects on various systems. Here, we synthesize key findings and illuminate promising avenues for future research in RASopathy biomarker discovery, underscoring rigorous validation and clinical translation.

Dermoscopic Features of Melanocytic Nevi in Cardiofaciocutaneous and Costello Syndromes.

Importance: Somatic variants in the RAS/MAPK pathway genes are commonly associated with melanocytic nevi and melanoma, whereas germline variants in these genes are associated with RASopathies, syndromes involving multiple organs, including the skin. Nevi counts may be higher in some RASopathies, but studies on features observed through dermoscopy are limited. Objective: To determine the distinguishing dermoscopic features of melanocytic nevi and how the RAS pathway influences them by comparing nevi in patients with cardiofaciocutaneous syndrome (CFC) and Costello syndrome (CS). Design, Setting, and Participants: In this prospective cohort study, patients with CFC and CS, 2 RASopathies caused by variants in the downstream and upstream components of the RAS/MAPK pathway, were recruited from the international CFC and CS family conferences. Some patients with CFC also elected to participate in a longitudinal follow-up study. Main Outcomes and Measures: The main outcomes were dermoscopic features and, in the longitudinal follow-up study, nevi counts, which were recorded over time. Results: A total of 39 patients, 16 with CFC and 23 with CS, were enrolled (overall cohort: 26 [66.7%] female; median [IQR] age, 13.0 [7.6-22.0] years). The 112 nevi overall frequently displayed an organized dermoscopic pattern (CFC, 61 [84.7%]; CS, 34 [85.0%]) rather than a disorganized pattern (CFC, 6 [8.3%]; CS, 1 [2.5%]). Of the organized nevi, homogenous brown was the most common pattern (CFC, 41 [67.2%]; CS, 22 [64.7%]), followed by reticular (CFC, 11 [18.0%]; CS, 7 [20.6%]) and globular (CFC, 9 [14.8%]; CS, 5 [14.7%]). Pigmented networks occurred in 12 nevi in CFC (16.7%) and 6 nevi in CS (15%; P > .99). Of these, 6 CFC-associated nevi (50%) and no CS-associated nevi had atypical networks (P = .05). Six patients with CFC in the follow-up study developed significantly more nevi within 5 years (median [IQR] increase, 24.5 [10-120] nevi; P = .04). Conclusions and Relevance: In this cohort study, the findings suggest that nevi in patients with CFC and CS commonly display organized homogenous brown dermoscopic patterns, and the number of nevi may significantly increase over time in those with CFC. A disorganized pattern and atypical networks may be more frequent in patients with CFC. Future studies are needed to determine the risk of melanoma in individuals with CFC or CS.

RASopathies for Radiologists.

RASopathies are a heterogeneous group of genetic syndromes caused by germline mutations in a group of genes that encode components or regulators of the Ras/mitogen-activated protein kinase (MAPK) signaling pathway. RASopathies include neurofibromatosis type 1, Legius syndrome, Noonan syndrome, Costello syndrome, cardiofaciocutaneous syndrome, central conducting lymphatic anomaly, and capillary malformation-arteriovenous malformation syndrome. These disorders are grouped together as RASopathies based on our current understanding of the Ras/MAPK pathway. Abnormal activation of the Ras/MAPK pathway plays a major role in development of RASopathies. The individual disorders of RASopathies are rare, but collectively they are the most common genetic condition (one in 1000 newborns). Activation or dysregulation of the common Ras/MAPK pathway gives rise to overlapping clinical features of RASopathies, involving the cardiovascular, lymphatic, musculoskeletal, cutaneous, and central nervous systems. At the same time, there is much phenotypic variability in this group of disorders. Benign and malignant tumors are associated with certain disorders. Recently, many institutions have established multidisciplinary RASopathy clinics to address unique therapeutic challenges for patients with RASopathies. Medications developed for Ras/MAPK pathway-related cancer treatment may also control the clinical symptoms due to an abnormal Ras/MAPK pathway in RASopathies. Therefore, radiologists need to be aware of the concept of RASopathies to participate in multidisciplinary care. As with the clinical manifestations, imaging features of RASopathies are overlapping and at the same time diverse. As an introduction to the concept of RASopathies, the authors present major representative RASopathies, with emphasis on their imaging similarities and differences. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Dermatological manifestations in Costello syndrome: A prospective multicentric study of 31 HRAS-positive variant patients.

BACKGROUND: Data on dermatological manifestations of Costello syndrome (CS) remain heterogeneous and lack in validated description. OBJECTIVES: To describe the dermatological manifestations of CS; compare them with the literature findings; assess those discriminating CS from other RASopathies, including cardiofaciocutaneous syndrome (CFCS) and the main types of Noonan syndrome (NS); and test for dermatological phenotype-genotype correlations. METHODS: We performed a 10-year, large, prospective, multicentric, collaborative dermatological and genetic study. RESULTS: Thirty-one patients were enrolled. Hair abnormalities were ubiquitous, including wavy or curly hair and excessive eyebrows, respectively in 68% and 56%. Acral excessive skin (AES), papillomas and keratotic papules (PKP), acanthosis nigricans (AN), palmoplantar hyperkeratosis (PPHK) and 'cobblestone' papillomatous papules of the upper lip (CPPUL), were noted respectively in 84%, 61%, 65%, 55% and 32%. Excessive eyebrows, PKP, AN, CCPUL and AES best differentiated CS from CFCS and NS. Multiple melanocytic naevi (>50) may constitute a new marker of attenuated CS associated with intragenic duplication in HRAS. Oral acitretin may be highly beneficial for therapeutic management of PPHK. No significant dermatological phenotype-genotype correlation was determined between patients with and without HRAS c.34G>A (p.G12S). CONCLUSIONS AND RELEVANCE: This validated phenotypic characterization of a large number of patients with CS will allow future researchers to make a positive diagnosis, and to differentiate CS from CFCS and NS.

Autism spectrum disorder profiles in RASopathies: A systematic review.

BACKGROUND: RASopathies are associated with an increased risk of autism spectrum disorder (ASD). For neurofibromatosis type 1 (NF1) there is ample evidence for this increased risk, while for other RASopathies this association has been studied less. No specific ASD profile has been delineated so far for RASopathies or a specific RASopathy individually. METHODS: We conducted a systematic review to investigate whether a specific RASopathy is associated with a specific ASD profile, or if RASopathies altogether have a distinct ASD profile compared to idiopathic ASD (iASD). We searched PubMed, Web of Science, and Open Grey for data about ASD features in RASopathies and potential modifiers. RESULTS: We included 41 articles on ASD features in NF1, Noonan syndrome (NS), Costello syndrome (CS), and cardio-facio-cutaneous syndrome (CFC). Individuals with NF1, NS, CS, and CFC on average have higher ASD symptomatology than healthy controls and unaffected siblings, though less than people with iASD. There is insufficient evidence for a distinct ASD phenotype in RASopathies compared to iASD or when RASopathies are compared with each other. We identified several potentially modifying factors of ASD symptoms in RASopathies. CONCLUSIONS: Our systematic review found no convincing evidence for a specific ASD profile in RASopathies compared to iASD, or in a specific RASopathy compared to other RASopathies. However, we identified important limitations in the research literature which may also account for this result. These limitations are discussed and recommendations for future research are formulated.

MEK Inhibition for RASopathy-Associated Hypertrophic Cardiomyopathy: Clinical Application of a Basic Concept.

The term "RASopathies" designates a group of developmental syndromes that are caused by activating variants of the rat sarcoma virus protein (RAS)/mitogen-activated protein kinase (MAPK) cascade. The most prevalent clinical diagnosis is Noonan syndrome, and other, less prevalent conditions include Noonan syndrome with multiple lentigines, Costello syndrome, cardiofaciocutaneous syndrome, and others. Hypertrophic cardiomyopathy occurs in 10% of these patients and can be severe and life-threating. Recently, repurposing of medications inhibiting the RAS/MAPK on a compassionate use basis has emerged as a promising concept to improve the outcome of these patients. Herein, we specifically review the role of the RAS/MAPK pathway in RASopathy-associated cardiomyopathy, and discuss the role of small-molecule inhibition in the treatment of this condition. We describe how drug repurposing of trametinib (mitogen-activated protein/extracellular signal-regulated kinase inhibition) and sirolimus/everolimus (mammalian target of rapamycin inhibition) was performed, how genotype-specific therapies are chosen and followed, as well as initial outcomes from early case series. Finally, we lay out the challenges and opportunities for trials that aim to quantify the benefits of this approach.

The 8th International RASopathies Symposium: Expanding research and care practice through global collaboration and advocacy.

Germline pathogenic variants in the RAS/mitogen-activated protein kinase (MAPK) signaling pathway are the molecular cause of RASopathies, a group of clinically overlapping genetic syndromes. RASopathies constitute a wide clinical spectrum characterized by distinct facial features, short stature, predisposition to cancer, and variable anomalies in nearly all the major body systems. With increasing global recognition of these conditions, the 8th International RASopathies Symposium spotlighted global perspectives on clinical care and research, including strategies for building international collaborations and developing diverse patient cohorts in anticipation of interventional trials. This biannual meeting, organized by RASopathies Network, was held in a hybrid virtual/in-person format. The agenda featured emerging discoveries and case findings as well as progress in preclinical and therapeutic pipelines. Stakeholders including basic scientists, clinician-scientists, practitioners, industry representatives, patients, and family advocates gathered to discuss cutting edge science, recognize current gaps in knowledge, and hear from people with RASopathies about the experience of daily living. Presentations by RASopathy self-advocates and early-stage investigators were featured throughout the program to encourage a sustainable, diverse, long-term research and advocacy partnership focused on improving health and bringing treatments to people with RASopathies.

Diagnosis, treatment planning, and comprehensive restoration of a patient with Costello syndrome: rationale and application of indirect composite resin onlays.

Patients with a complex problem set involving multiple levels of altered structure challenge the clinician to develop an individualized, appropriate treatment plan. Dentofacial deficiency, occlusal problems, and loss of tooth structure require intervention to establish stability and regain function, speech, esthetics, and masticatory muscle comfort. The comprehensive examination must quantify each problem to specify the diagnosis for realistic treatment planning. The clinical case of a patient with Costello syndrome is presented to illustrate essential concepts in diagnosis and treatment of complex cases, including (1) Global Diagnosis of anterior esthetic relationships, (2) occlusal analysis with diagnostic casts verified in centric relation, (3) comprehensive restoration previewed with a diagnostic wax-up and removable acrylic resin overlay, (4) adhesive monobody composite resin onlays that preserve tooth structure, and (5) programmed occlusion, quantified with digital occlusal analysis, to ensure stability and comfort. Costello syndrome is a neurodevelopmental syndrome causing multisystem effects, including a distinctive craniofacial phenotype, cardiovascular disease, intellectual disability, growth hormone deficiency, and dental abnormalities such as delayed dental development, bruxism, and demineralized enamel lesions. In the present case, quantification of the patient's problem set allowed precise treatment planning that resulted in predictable restoration.

RASopathies and spinal deformities for screening of scoliosis.

BACKGROUND: The RASopathies (Noonan syndrome [NS] and Costello syndrome [CS]) are rare disorders. Although these have been characterized, precise delineation of the differences in the spinal deformities associated with RASopathy has not been described. This study characterized the spinal deformities found in NS and CS and describes a strategy for the screening of scoliosis. METHODS: The clinical records and spinal X-rays of 35 consecutive NS and CS patients were reviewed. Spinal X-rays were assessed to define the presence and progression of scoliosis. Clinical records were examined to identify the risk factors associated with scoliosis. In addition, we investigated the association between clinical records and scoliosis using logistic regression analysis. RESULTS: Twenty-four patients with NS and 11 with CS were included. Nine patients with NS and five with CS showed scoliosis. The mean ± SD age at diagnosis was 12.6 ± 2.4 years in NS and 11.4 ± 2.5 years in CS (p = 0.55), and mean follow-up period was 4.8 ± 2.6 years and 6.3 ± 2.4 years (p = 0.42), respectively. The coronal angular deformity at final follow-up was 27.3 ± 8.5° in NS and 19.4 ± 6.9° in CS (p = 0.030) with a mean annual progression of 2.8 ± 1.1° in NS 1.0 ± 1.0° in CS (p = 0.030). Cardiac disease was present in eight out of nine patients with NS with concomitant scoliosis in NS, and significantly more than in CS (p = 0.007). PTPN11 significantly correlated with scoliosis (odds ratio 12.4 0.035, 95% confidence interval: 1.20-128.00). CONCLUSIONS: Spinal deformity in NS is more severe than in CS. This study identified a relationship between PTPN11 and scoliosis. Therefore, PTPN11 can be used for the screening of scoliosis.

Fatal leukodystrophy in Costello syndrome: a case report.

BACKGROUND: Costello syndrome (CS) is a rare genetic condition characterized by dysregulation of the signaling pathway, phenotypic alteration due to fetal macrosomia or growth retardation, facial abnormalities, loose skin, cardiovascular abnormalities, and a variable degree of intellectual disability. CASE PRESENTATION: We describe the case of a 20-month-old male patient with fetal macrosomia and polyhydramnios, presenting psychomotor development delay and growth limitation during the first months of life. CS was diagnosed at four months of age after detecting a variant of the HRAS gene c.35G > C (p.G12A). A clinical description of his condition was recorded throughout his life, including cardiovascular diseases, endocrine disorders, and recurrent infections. At 20 months of age, after presenting events of marked hypotonia and generalized seizures, brain magnetic resonance revealed symmetrical lesions of the infra- and supratentorial white matter in both cerebral hemispheres, which resulted in the diagnosis of cerebral leukodystrophy. The patient had a rapid and progressive deterioration that eventually led to death. CONCLUSIONS: This is the first report of a case of CS in Peru. In addition, this is a case that presented with multisystemic conditions culminating in leukodystrophy, which is a rare event according to the literature.

A very mild phenotype in six individuals of a three-generation family with the novel HRAS variant c.176C > G p.(Ala59Gly): Emergence of a new HRAS-related RASopathy distinct from Costello syndrome.

Costello syndrome is a clinically recognizable, severe neurodevelopmental disorder caused by heterozygous activating variants in HRAS. The vast majority of affected patients share recurring variants affecting HRAS codons 12 and 13 and a relatively uniform phenotype. Here, we report the unique and attenuated phenotype of six individuals of an extended family affected by the HRAS variant c.176C>T p.(Ala59Gly), which, to our knowledge, has never been reported as a germline variant in patients so far. HRAS Alanine 59 has been previously functionally investigated as an oncogenic hotspot and the p.Ala59Gly substitution was shown to impair intrinsic GTP hydrolysis. All six individuals we report share a phenotype of ectodermal anomalies and mild features suggestive of a RASopathy, reminiscent of patients with Noonan syndrome-like disorder with loose anagen hair. All six are of normal intelligence, none have a history of failure to thrive or malignancy, and they have no known cardiac or neurologic pathologies. Our report adds to the previous reports of patients with rare variants affecting amino acids located in the SWITCH II/G3 region of HRAS and suggests a consistent, attenuated phenotype distinct from classical Costello syndrome. We propose the definition of a new distinct HRAS-related RASopathy for patients carrying HRAS variants affecting codons 58, 59, 60.

Cancer in Costello syndrome: a systematic review and meta-analysis.

BACKGROUND: Costello syndrome (CS) is a cancer-predisposition disorder caused by germline pathogenic variants in HRAS. We conducted a systematic review using case reports and case series to characterise cancer risk in CS. METHODS: We conducted a systematic review to identify CS cases to create a retrospective cohort. We tested genotype-phenotype correlations and calculated cumulative incidence and hazard rates (HR) for cancer and cancer-free death, standardised incidence rates (SIR) and survival after cancer. RESULTS: This study includes 234 publications reporting 621 patients from 35 countries. Over nine percent had cancer, including rhabdomyosarcoma, bladder, and neuroblastoma. The rate of cancer and death associated with p.Gly12Ser were lower when compared to all other variants (P < 0.05). Higher mortality for p.Gly12Cys, p.Gly12Asp, p.Gly12Val and p.Gly60Val and higher malignancy rate for p.Gly12Ala were confirmed (P < 0.05). Cumulative incidence by age 20 was 13% (cancer) and 11% (cancer-free death). HR (death) was 3-4% until age 3. Statistically significant SIRs were found for rhabdomyosarcoma (SIR = 1240), bladder (SIR = 1971), and neuroblastoma (SIR = 60). Survival after cancer appeared reduced. CONCLUSIONS: This is the largest investigation of cancer in CS to date. The high incidence and SIR values found to highlight the need for rigorous surveillance and evidence-based guidelines for this high-risk population.

How common are ear, nose and throat disorders in children with Noonan syndrome and other RASopathies?

INTRODUCTION: Noonan syndrome and related conditions (RASopathies) are known to be associated with abnormalities in many organ systems. It is our impression that few otolaryngologists are familiar with the manifestations of these syndromes and we therefore reviewed our hospital's patient cohort to identify the prevalence of ear, nose and throat disorders in these children. METHODS: We cross-referenced various hospital department databases (otolaryngology, audiology, cardiology, haematology and genetics) to try to identify as many children with Noonan and other RASopathies as possible. We then performed a retrospective review of electronic patient records. RESULTS: We identified 67 children with Noonan, Costello, LEOPARD and other RASopathy syndromes. Around half have been seen in otolaryngology and audiology clinics. Otitis media with effusion requiring ventilation tubes occurred in 4% of children. 10% have suffered recurrent acute otitis media. 9% have a sensorineural hearing loss. 7% have undergone adenotonsillectomy for obstructive sleep apnoea. Airway anomalies and head and neck malformations occur but are rare. DISCUSSION: Children with Noonan and other RASopathies present commonly to otolaryngology and audiology clinics. The prevalence of sensorineural hearing loss is high and audiological screening is likely to be worthwhile. Surgeons should be aware that complications of surgery are common and can be very severe, especially in those with cardiac anomalies.

Cutaneous manifestations in Costello syndrome: HRAS p.Gly12Ser affects RIN1-mediated integrin trafficking in immortalized epidermal keratinocytes.

Heterozygous germline missense variants in the HRAS gene underlie Costello syndrome (CS). The molecular basis for cutaneous manifestations in CS is largely unknown. We used an immortalized human cell line, HaCaT keratinocytes, stably expressing wild-type or CS-associated (p.Gly12Ser) HRAS and defined RIN1 as quantitatively most prominent, high-affinity effector of active HRAS in these cells. As an exchange factor for RAB5 GTPases, RIN1 is involved in endosomal sorting of cell-adhesion integrins. RIN1-dependent RAB5A activation was strongly increased by HRASGly12Ser, and HRAS-RIN1-ABL1/2 signaling was induced in HRASWT- and HRASGly12Ser-expressing cells. Along with that, HRASGly12Ser expression decreased total integrin levels and enriched ß1 integrin in RAB5- and EEA1-positive early endosomes. The intracellular level of active ß1 integrin was increased in HRASGly12Ser HaCaT keratinocytes due to impaired recycling, whereas RIN1 disruption raised ß1 integrin cell surface distribution. HRASGly12Ser induced co-localization of ß1 integrin with SNX17 and RAB7 in early/sorting and late endosomes, respectively. Thus, by retaining ß1 integrin in intracellular endosomal compartments, HRAS-RIN1 signaling affects the subcellular availability of ß1 integrin. This may interfere with integrin-dependent processes as we detected for HRASGly12Ser cells spreading on fibronectin. We conclude that dysregulation of receptor trafficking and integrin-dependent processes such as cell adhesion are relevant in the pathobiology of CS.