Phenotypic spectrum of Costello syndrome individuals harboring the rare HRAS mutation p.Gly13Asp

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.

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.

Management of nutritional and gastrointestinal issues in RASopathies: A narrative review

Noonan, Costello, and cardio-facio-cutaneous syndrome are neurodevelopmental disorders belonging to the RASopathies, a group of syndromes caused by alterations in the RAS/MAPK pathway. They are characterized by similar clinical features, among which feeding difficulties, growth delay, and gastro-intestinal disorders are frequent, causing pain and discomfort in patients. Hereby, we describe the main nutritional and gastrointestinal issues reported in individuals with RASopathies, specifically in Noonan syndrome, Noonan syndrome-related disorders, Costello, and cardio-facio-cutaneous syndromes. Fifty percent of children with Noonan syndrome may experience feeding difficulties that usually have a spontaneous resolution by the second year of life, especially associated to genes different than PTPN11 and SOS1. More severe manifestations often require artificial enteral nutrition in infancy are observed in Costello syndrome, mostly associated to c.34G>A substitution in the HRAS gene. In cardio-facio-cutaneous syndrome feeding issues are usually present (90-100% of cases), especially in individuals carrying variants in BRAF, MAP2K1, and MAP2K2 genes, and artificial enteral intervention, even after scholar age, may be required. Moreover, disorders associated with gastrointestinal dysmotility as gastro-esophageal reflux and constipation are commonly reported in all the above-mentioned syndromes. Given the impact on growth and on the quality of life of these patients, early evaluation and prompt personalized management plans are fundamental.

Multidisciplinary Management of Costello Syndrome: Current Perspectives

Costello syndrome (CS) is a rare neurodevelopmental disorder caused by germline mutations in HRAS. It belongs among the RASopathies, a group of syndromes characterized by alterations in components of the RAS/MAPK signaling pathway and sharing overlapping phenotypes. Its typical features include a distinctive facial appearance, growth delay, intellectual disability, ectodermal, cardiac, and musculoskeletal abnormalities, and cancer predisposition. Due to the several comorbidities having a strong impact on the quality of life, a multidisciplinary team is essential in the management of such a condition from infancy to adult age, to promptly address any detected issue and to develop appropriate personalized follow-up protocols and treatment strategies. With the present paper we aim to highlight the core and ancillary medical disciplines involved in managing the health challenges characterizing CS from pediatric to adult age, according to literature and to our large clinical experience.

Clinical and molecular characterization of Costello syndrome in unrelated Mexican patients

This study intends to describe for the first time a cohort of Mexican patients with Costello syndrome. The five exons of the HRAS gene were amplified in DNA samples from 13 patients with a clinical suspicion of Costello syndrome. PCR products were sequenced using the Ready Reaction Big Dye Terminator v.3.0 Kit and an ABI PRISM 310 sequencer. Only five patients (38%) showed causal variant in codon 12 of the HRAS gene (four with the p.Gly12Ser and one with the p.Gly12Ala variant). Three patients showed silent polymorphic variants (p.His27His and p.Leu159Leu). Clinical features in patients carrying the causal variant were variable. The alternative diagnosis of cardio-facio-cutaneous syndrome was considered in patients who did not have a causative variant in HRAS.

Lymphatic Abnormalities in Noonan Syndrome Spectrum Disorders: A Systematic Review

Noonan syndrome spectrum disorders are a group of phenotypically related conditions, resembling Noonan syndrome, caused by germline pathogenic variants in genes within the Ras/mitogen-activated protein kinase (Ras/MAPK) signalling pathway. Lymphatic dysplasia with a clinical lymphatic abnormality is one of the major features. We performed a systematic review to get more insight in (1) the prevalence of clinically lymphatic abnormalities in patients with a genetically proven Noonan syndrome spectrum disorder, (2) if a genotype-lymphatic phenotype relation can be found and describe the clinical presentation and course of the lymphatic abnormality. Most studies report patients with Noonan syndrome. Prenatally, the prevalence of increased nuchal translucency differs from 7% in patients with pathogenic PTPN11 variants to 38% in patients with pathogenic RIT1 variants, and the prevalence of pleural effusions differed from 7% in patients with pathogenic SOS1 to 29% in patients with pathogenic RIT1 variants. Postnatally, the prevalence of lymphedema differs from 16% in patients with pathogenic PTPN11 variants to 44% in patients with pathogenic SOS1 variants, and the prevalence of acquired chylothorax is 4% in patients with pathogenic RIT1 variants. Lymphatic abnormalities do occur in patients with cardiofaciocutaneous syndrome and Costello syndrome. In conclusion, Noonan syndrome spectrum disorders, Noonan syndrome in particular, are associated with lymphatic abnormalities. Combining the available published literature about genetically proven Noonan syndrome spectrum disorders, it appears likely that the lifetime prevalence of these abnormalities in Noonan syndrome is higher than the 20% that were generally accepted so far. This is increasingly important, because the activation of the RAS/MAPK pathway can be inhibited by RAS/MAPK inhibitors, and clinically severe lymphatic abnormalities may improve.

Bone tissue homeostasis and risk of fractures in Costello syndrome: A 4-year follow-up study

Costello syndrome (CS) is a neurodevelopmental disorder with a distinctive musculoskeletal phenotype and reduced bone mineral density (BMD) caused by activating de novo mutations in the HRAS gene. Herein, we report the results of a prospective study evaluating the efficacy of a 4-year vitamin D supplementation on BMD and bone health. A cohort of 16 individuals ranging from pediatric to adult age with molecularly confirmed CS underwent dosages of bone metabolism biomarkers (serum/urine) and dual-energy X-ray absorptiometry (DXA) scans to assess bone and body composition parameters. Results were compared to age-matched control groups. At baseline evaluation, BMD was significantly reduced (p ≤ 0.05) compared to controls, as were the 25(OH)vitD levels. Following the 4-year time interval, despite vitamin D supplementation therapy at adequate dosages, no significant improvement in BMD was observed. The present data confirm that 25(OH)vitD and BMD parameters are reduced in CS, and vitamin D supplementation is not sufficient to restore proper BMD values. Based on this evidence, routine monitoring of bone homeostasis to prevent bone deterioration and possible fractures in adult patients with CS is highly recommended.

Costello syndrome with special cutaneous manifestations and HRAS G12D mutation: A case report and literature review

Background

Costello syndrome (CS, OMIM 218040) is a rare congenital disorder caused by mutations in HRAS. Previous studies reported that approximately 80% of patients with CS share the same pathogenic variant in HRAS gene in c.34G> A (p.G12S). Here, we report a CS patient with c.34G> A (p.G12D) variant in HRAS gene and she presented with special manifestation.

Methods and Results

We describe a 31‐year‐old female patient who presented with distinctive facial appearance, intellectual disability, dental abnormalities, hyperkeratosis of palmer and planter, loose skin at birth, papillomata on the face and nipples. The whole‐exome sequencing (WES) technology provided by Haotian Biotechnology (China) confirmed p.G12D variant in HRAS gene. To elucidate the typical features of CS with p.G12D variant, we further reviewed these previously reported cases and found that patients with G12D variant died within three months after birth due to multiple organ failure. They had the typical facial characteristics, failure to thrive, skin and cardiac abnormalities, and gene testing confirmed the diagnosis of CS.

Conclusion

To the best of our knowledge, this is the first article to report a patient with a p.G12D variant that had special but mild manifestation. Moreover, this report and literature review casts new light on the clinical features of p.G12D variant.

Recombinant GH treatment in a case of Costello syndrome with a 5-year follow-up

Costello syndrome (CS) is a rare member of the group of neuro-cardio-facio-cutaneous diseases known as RASopathies. CS involves characteristic dysmorphic craniofacial features, cardiac defects, and increased cancer susceptibility, depending on the heterozygous activating germline mutations in HRAS. Polyhydramnios and high birth weight are the most common presentations in the perinatal and neonatal periods; while poor postnatal growth, short stature, and failure to thrive are significant issues in infancy. Possible mechanisms of short stature in CS include GH deficiency and feeding difficulties. Only a few reported cases of CS with GH deficiency exist in literature. Here, we describe the 5-yr follow-up of a CS patient with complete GH deficiency treated with recombinant human GH (rhGH) from the age of four years. No significant adverse events regarding progression of hypertrophic cardiomyopathy and tumor development were observed. She has been responsive to treatment with improved growth velocity and height standard deviation scores. She is still under continuous monitoring for concerns on the possible development of cardiac events and malignancies. This case indicated that rhGH therapy is effective for improving the height and growth velocity of CS patients with GH deficiency under close cardiac and oncological monitoring.

Phenotypic and Genetic Characteristics of Five Korean Patients with Costello Syndrome

Costello syndrome (CS) is a rare genetic disorder characterized by distinctive facial appearance, cardiopulmonary complications, severe growth retardation, skin and skeletal defects, developmental delay, and tumor predisposition. CS is caused by heterozygous de novo mutations in the proto-oncogene HRAS, which is a component of the RAS/mitogen-activated protein kinase pathway. Herein, we reviewed the phenotypic and genetic features of 5 Korean patients who were genetically diagnosed with CS. Atrial tachycardia and polyhydramnios, which are important prenatal features for CS, were observed in 4 and 5 patients, respectively. The distinctive coarse facial appearances of the patients and presence of deep palmoplantar creases supported the clinical diagnosis of CS, which was confirmed by HRAS sequence analysis. Extremely poor postnatal growth was observed in all 5 patients. Further, all patients exhibited cardiac abnormalities; left ventricular hypertrophy and hypertrophic cardiomyopathy were observed in 3 patients. All 5 patients suffered from airway problems; 3 of them required intubation right after birth, and 2 of them received tracheostomy. One patient with a p.Gly12Ser mutation was diagnosed with retroperitoneal rhabdomyosarcoma alveolar type at the age of 5 years. Consistent with previous reports, both patients with p.Gly12Cys mutations died within the first year of life due to cardiopulmonary failure. Our study summarizes the characteristics of these 5 Korean patients with CS and, along with previous studies, provides clues for genotype-phenotype correlation in patients with CS.

Activating Mutations of RRAS2 Are a Rare Cause of Noonan Syndrome

Aberrant signaling through pathways controlling cell response to extracellular stimuli constitutes a central theme in disorders affecting development. Signaling through RAS and the MAPK cascade controls a variety of cell decisions in response to cytokines, hormones, and growth factors, and its upregulation causes Noonan syndrome (NS), a developmental disorder whose major features include a distinctive facies, a wide spectrum of cardiac defects, short stature, variable cognitive impairment, and predisposition to malignancies. NS is genetically heterogeneous, and mutations in more than ten genes have been reported to underlie this disorder. Despite the large number of genes implicated, about 10%-20% of affected individuals with a clinical diagnosis of NS do not have mutations in known RASopathy-associated genes, indicating that additional unidentified genes contribute to the disease, when mutated. By using a mixed strategy of functional candidacy and exome sequencing, we identify RRAS2 as a gene implicated in NS in six unrelated subjects/families. We show that the NS-causing RRAS2 variants affect highly conserved residues localized around the nucleotide binding pocket of the GTPase and are predicted to variably affect diverse aspects of RRAS2 biochemical behavior, including nucleotide binding, GTP hydrolysis, and interaction with effectors. Additionally, all pathogenic variants increase activation of the MAPK cascade and variably impact cell morphology and cytoskeletal rearrangement. Finally, we provide a characterization of the clinical phenotype associated with RRAS2 mutations.

The Ras Superfamily of Small GTPases in Non-neoplastic Cerebral Diseases

The small GTPases from the Ras superfamily play crucial roles in basic cellular processes during practically the entire process of neurodevelopment, including neurogenesis, differentiation, gene expression, membrane and protein traffic, vesicular trafficking, and synaptic plasticity. Small GTPases are key signal transducing enzymes that link extracellular cues to the neuronal responses required for the construction of neuronal networks, as well as for synaptic function and plasticity. Different subfamilies of small GTPases have been linked to a number of non-neoplastic cerebral diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), intellectual disability, epilepsy, drug addiction, Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS) and a large number of idiopathic cerebral diseases. Here, we attempted to make a clearer illustration of the relationship between Ras superfamily GTPases and non-neoplastic cerebral diseases, as well as their roles in the neural system. In future studies, potential treatments for non-neoplastic cerebral diseases which are based on small GTPase related signaling pathways should be explored further. In this paper, we review all the available literature in support of this possibility.

A case of woolly hair nevus, multiple linear pigmentation, and epidermal nevi with somatic HRAS p.G12S mutation

Woolly hair nevus is a rare syndrome that presents as woolly hair in restricted areas of the scalp and may be associated with pigmented macules or epidermal nevus on the body. Here, we report a case of woolly hair nevus, linear pigmentation, and multiple epidermal nevi with a somatic HRAS c.34G>A(p.G12S) mutation.

RAS GTPase-dependent pathways in developmental diseases: old guys, new lads, and current challenges

Deregulated RAS signaling is associated with increasing numbers of congenital diseases usually referred to as RASopathies. The spectrum of genes and mutant alleles causing these diseases has been significantly expanded in recent years. This progress has triggered new challenges, including the origin and subsequent selection of the mutations driving these diseases, the specific pathobiological programs triggered by those mutations, the type of correlations that exist between the genotype and the clinical features of patients, and the ancillary genetic factors that influence the severity of the disease in patients. These issues also directly impinge on the feasibility of using RAS pathway drugs to treat RASopathy patients. Here, we will review the main developments and pending challenges in this research topic.

Cardiac defects, morbidity and mortality in patients affected by RASopathies. CARNET study results

BACKGROUND

RASopathies are developmental disease caused by mutations in genes encoding for signal transducers of the RAS-MAPK cascade. The aim of the present study was to provide a comprehensive description of morbidity and mortality in patients with molecularly confirmed RASopathy.

METHODS

A multicentric, observational, retrospective study was conducted in seven European cardiac centres participating to the CArdiac Rasopathy NETwork (CARNET). Clinical records of 371 patients with confirmed molecular diagnosis of RASopathy were reviewed. Mortality was described as crude mortality, cumulative survival and restricted estimated mean survival. Multivariable regression analysis was used to assess the impact of mutated genes on number of interventions and overall prognosis.

RESULTS

Cardiac defects occurred in 80.3% of cases, almost half of them underwent at least one intervention. Overall, crude mortality was 0.29/100 patients-year. Cumulative survival was 98.8%, 98.2%, 97.7%, 94.3%, at 1, 5, 10, and 20years, respectively. Restricted estimated mean survival at 20years follow-up was 19.6years. Ten patients died (2.7% of the entire cohort; 3.4% of patients with cardiac defect). Patients with hypertrophic cardiomyopathy (HCM) and age <2years or young adults, as well as subjects with biventricular obstruction and PTPN11 mutations had a higher risk of cardiac death.

CONCLUSIONS

The risk of intervention was higher in individuals with Noonan syndrome and pulmonary stenosis carrying PTPN11 mutations. Overall, mortality was relatively low, even though the specific association between HCM, biventricular outflow tract obstructions and PTPN11 mutations appeared to be associated with early mortality, including immediate post-operative events and sudden death.