Dermatological manifestations in cardiofaciocutaneous syndrome: a prospective multicentric study of 45 mutation-positive patients

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.

The Cardiofaciocutaneous Syndrome: From Genetics to Prognostic-Therapeutic Implications

Cardiofaciocutaneous (CFC) syndrome is one of the rarest RASopathies characterized by multiple congenital ectodermal, cardiac and craniofacial abnormalities with a mild to severe ocular, gastrointestinal and neurological involvement. It is an autosomal dominant syndrome, with complete penetrance, caused by heterozygous pathogenic variants in the genes BRAF, MAP2K1/MEK1, MAP2K2/MEK2, KRAS or, rarely, YWHAZ, all part of the RAS-MAPK pathway. This pathway is a signal transduction cascade that plays a crucial role in normal cellular processes such as cell growth, proliferation, differentiation, survival, metabolism and migration. CFC syndrome overlaps with Noonan syndrome, Costello syndrome, neurofibromatosis type 1 and Legius syndrome, therefore making the diagnosis challenging. Neurological involvement in CFC is more severe than in other RASopathies. Phenotypic variability in CFC patients is related to the specific gene affected, without a recognized genotype-phenotype correlation for distinct pathogenic variants. Currently, there is no specific treatment for CFC syndrome. Encouraging zebrafish model system studies suggested that, in the future, MEK inhibitors could be a suitable treatment of progressive phenotypes of CFC in children. A multidisciplinary care is necessary for appropriate medical management.

Diverse Clinical Manifestations of Cardiofaciocutaneous Syndrome Type 3 in Two Patients from South East Asia

Background

Cardiofaciocutaneous syndrome (CFCS) is a rare genetic condition caused by mutations in BRAF, KRAS, MAP2K1, or MAP2K2. It is characterized by ectodermal abnormalities, cardiac defects, intellectual disability, and distinct craniofacial features. CFCS falls under a group of conditions caused by mutations in the RAS/MAPK pathway called RASopathies which share many features. In particular, CFCS has significant phenotypic overlaps with Costello syndrome (CS) and Noonan syndrome (NS).

Objective

The aim of this study was to assess the patients‧ phenotypic features for syndromic disorders and evaluate the use of molecular testing to clarify the clinical diagnosis.

Method

The patients were recruited for genetic testing with written informed consent. Genomic DNA from venous blood was sequenced and potential variants were identified via targeted next-generation sequencing. Their phenotypic features were compared with other CFCS cases carrying pathogenic variants in the same gene.

Results and Discussion

One patient had a de novo variant (c.370C>T; p.P124S) in MAP2K1 and presented with mild and typical features which do not significantly affect her quality of life. The second patient presented with severe features, including failure to thrive, feeding difficulties, epileptic spasms, septal hypertrophy, and global developmental delay, and developed chronic lung disease and sequelae from multiple infections. She had a severe disease course and severe global developmental delay. The discovery of a de novo variant (c.371C>A; p.P124Q) in MAP2K1, which had been reported in another patient with a similar phenotype, clarifies her clinical diagnosis. Her presentations add to existing reports that support expanding the CFCS phenotype to include features previously thought to be more suggestive of CS.

Conclusion

The genetic findings for the 2 patients affirm the use of identified gene mutations to confirm the clinical diagnosis of syndromic disorders and add to the phenotypic spectrum of CFCS.

Clinical overview on RASopathies

RASopathies comprise a group of clinically overlapping developmental disorders caused by genetic variations affecting components or modulators of the RAS-MAPK signaling cascade, which lead to dysregulation of signal flow through this pathway. Noonan syndrome and the less frequent, clinically related disorders, Costello syndrome, cardiofaciocutaneous syndrome, Noonan syndrome with multiple lentigines, and Noonan syndrome-like disorder with loose anagen hair are part of the RASopathy spectrum and share a recognizable pattern of multisystem involvement. This review describes the "Noonan syndrome-like" phenotype as a common phenotypic signature of generalized developmental RAS pathway dysregulation. Distinctive features of the different entities are revisited against the background of the understanding of underlying genetic alterations and genotype correlations, which has evolved rapidly during the past 20 years, thereby leading to suggestions regarding the nosology of RASopathies.

Dermatological manifestations, management, and care in RASopathies

RASopathies are rare genetic disorders caused by germline pathogenic variants in genes belonging to the RAS/MAPK pathway, which signals cell proliferation, differentiation, survival and death. The dysfunction of such signaling pathway causes syndromes with overlapping clinical manifestations. Skin and adnexal lesions are the cardinal clinical signs of RASopathies, such as cardiofaciocutaneous syndrome, Noonan syndrome with multiple lentigines, formerly known as LEOPARD syndrome, Costello syndrome, neurofibromatosis (NF1), Legius syndrome, Noonan-like syndrome with loose anagen hair (NSLH) and Noonan syndrome. As NF1, one of the most common RASopathies, described in 1882, has its clinical features well delineated, we will focus on the dermatological diagnosis, management and care of non-NF1 RASopathies, which are less known and more recently described. Dermatological manifestations are important clinical diagnostic elements that can aid differential diagnosis among RASopathies. They can affect dermis and epidermis, causing pigmented lesions (melanocytic nevi, café-au-lait spots, and lentigines), hyperkeratosis (keratosis pilaris, ulerythema ophryogenes, and palmoplantar keratosis) or hyperplasia. To date there are rare known links to malignancy, but oftentimes skin lesions require close attention because they can highly affect quality of life.

Genodermatoses associated with melanocytic nevi

Though melanocytic nevi are ubiquitous in the general population, they can also be key cutaneous manifestations of genetic syndromes. We describe genodermatoses associated with melanocytic nevi and discuss their clinical characteristics, cutaneous manifestations, underlying genetics, and, if applicable, guidelines for when genetic testing should be performed. We categorized these genodermatoses based on their association with congenital nevi, acquired nevi, or nevi whose first appearance is unknown. In many cases, the distinctive morphology or distribution of melanocytic nevi can be an important clue that an underlying genetic syndrome is present, allowing both the patient as well as family members to be screened for the more serious complications of their genetic disorder and receive education on potential preventative measures. As we continue to advance our understanding of how various genotypes give rise to the wide spectrum of phenotypes observed in these genodermatoses, we shall be able to better stratify risk and tailor our screening methods to clinically manage the heterogeneous manifestations of genodermatoses among these patients.

RASopathies: Dermatologists’ viewpoints

Ras/mitogen-activated protein kinase pathway dysregulation results in a group of disorders, collectively termed as RASopathies. Neurofibromatosis type 1, Noonan syndrome, Noonan syndrome with multiple lentigines, Noonan syndrome/loose anagen hair, Legius syndrome, Costello syndrome, cardio-facio-cutaneous syndrome and capillary malformation-arteriovenous malformation are the well-recognized RASopathies. These are characterized by multi-organ tumours and hamartomas. Some other features in common are facial dysmorphism, skeletal abnormalities, congenital heart disease, neurocognitive abnormalities and risk of various solid-organ and haematological malignancies. Some of the RASopathies are heterogeneous, caused by several gene mutations resulting in variations in phenotypes and severity ranging from mild to fatal. Significant phenotypic overlaps among different disorders, often makes it difficult to pinpoint a clinical diagnosis. Specific cutaneous manifestations are present in some of the RASopathies and are often the earliest clinical signs/symptoms. Hence, dermatologists contribute significantly as primary care physicians by identifying disorder-specific cutaneous lesions. However, diagnostic work-up and management of these disorders are often multidisciplinary. Confirmation of diagnosis is possible only by genetic mapping in each case. Genetic counseling of the patients and the affected families is an important component of the management. The aim of this review is description of cutaneous manifestations of RASopathies in the background of multi-system involvement to enable dermatologists a comprehensive and logical approach to work up and diagnose such patients in the absence of facility for specific molecular testing.

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Costello syndrome model mice with a HrasG12S/+ mutation are susceptible to develop house dust mite-induced atopic dermatitis

Costello syndrome is an autosomal dominant disorder that is caused by germline HRAS mutations. Patients with Costello syndrome present craniofacial abnormalities, cardiac defects, and cancer predisposition, as well as skin abnormalities, including papillomas, keratosis pilaris, and eczematous dermatitis. However, the mechanisms underlying the dermatological abnormalities remain unclear. Here, we demonstrated that knock-in mice expressing an Hras G12S mutation (Hras^G12S/+ mice) are susceptible to develop atopic dermatitis (AD)-like skin lesions, including eczema, pruritus, elevated serum IgE levels, acanthosis, and the infiltration of mast cells, basophils, and type-2 innate lymphoid cells in the dermis, after stimulation with house dust mite allergens (Dermatophagoides farinae, Dfb). Reduced skin barrier function, increased proliferation of phosphorylated ERK (p-ERK)-positive epidermal cells, and increased Th2-type cytokines as well as epithelial cell-derived cytokines, including IL-33, were observed in the skin tissue of Hras^G12S/+ mice compared with Hras^+/+ mice. Cultured Hras^G12S/+ keratinocytes exhibited increased IL-33 expression after Dfb stimulation. PD0325901, an MEK inhibitor, ameliorated AD-like symptoms in Hras^G12S/+ mice, showing decreased proliferation of p-ERK-positive epidermal cells and decreased expression of IL-33. Our findings indicate that the epidermis of Hras^G12S/+ mice stimulated by Dfb strongly induced IL-33 expression and type-2 innate lymphoid cells, resulting in AD-like skin lesions. These results suggest that the epidermis of Hras^G12S/+ mice are prone to development of eczematous dermatitis stimulated with house dust mite allergens.

Comparison of hair manifestations in cardio-facio-cutaneous and Costello syndromes highlights the influence of the RAS pathway on hair growth

BACKGROUND

Abnormal hair growth is a defining feature of RASopathies, syndromes caused by germline mutations in the RAS pathway. However, detailed hair manifestations and the mechanisms of altered hair growth in RASopathies are poorly delineated.

OBJECTIVES

To identify distinguishing clinical features and investigate how the RAS pathway influences hair growth by performing a systematic and detailed side-by-side comparison of hair manifestations in cardio-facio-cutaneous syndrome (CFCS) and Costello syndrome (CS), two RASopathies caused by mutations in the downstream and upstream elements of the RAS pathway, respectively.

METHODS

Sixteen individuals with CFCS and 23 individuals with CS were enrolled. Mutation data were recorded. Scalp hair, eyebrows and eyelashes of individuals with CFCS or CS were examined for texture, colour, density and morphology. Scalp hairs were examined by light microscopy.

RESULTS

While both syndromes displayed abnormal hair, striking differences were observed, including darker and thicker scalp hair and sparse eyebrows and eyelashes in CFCS. By contrast, synophrys, trichomegaly and abnormalities of the scalp hair shafts were observed in CS. Possible correlation with straight hair and genotype was observed in CS.

CONCLUSION

The results emphasize the role of the RAS pathway in hair growth, improve accuracy of clinical diagnosis of CFCS and CS and provide a foundation for identification of therapeutic targets.

Dermatological manifestations in Noonan syndrome: a prospective multicentric study of 129 patients positive for mutation

BACKGROUND

Data on dermatological manifestations of Noonan syndrome (NS) remain heterogeneous and are based on limited dermatological expertise.

OBJECTIVES

To describe the dermatological manifestations of NS, compare them with the literature findings, and test for dermatological phenotype-genotype correlations with or without the presence of PTPN11 mutations.

METHODS

We performed a large 4-year, prospective, multicentric, collaborative dermatological and genetic study.

RESULTS

Overall, 129 patients with NS were enrolled, including 65 patients with PTPN11-NS, 34 patients with PTPN11-NS with multiple lentigines (NSML), and 30 patients with NS who had a mutation other than PTPN11. Easy bruising was the most frequent dermatological finding in PTPN11-NS, present in 53·8% of patients. Multiple lentigines and café-au-lait macules (n ≥ 3) were present in 94% and 80% of cases of NSML linked to specific mutations of PTPN11, respectively. Atypical forms of NSML could be associated with NS with RAF1 or NRAS mutations. In univariate analysis, patients without a PTPN11 mutation showed (i) a significantly higher frequency of keratinization disorders (P = 0·001), including keratosis pilaris (P = 0·005), ulerythema ophryogenes (P = 0·0001) and palmar and/or plantar hyperkeratosis (P = 0·06, trend association), and (ii) a significantly higher frequency of scarce scalp hair (P = 0·035) and scarce or absent eyelashes (P = 0·06, trend association) than those with PTPN11 mutations.

CONCLUSIONS

The cutaneous phenotype of NS with a PTPN11 mutation is generally mild and nonspecific, whereas the absence of a PTPN11 mutation is associated with a high frequency of keratinization disorders and hair abnormalities.