CFC症候群

BACKGROUND: Dysregulation of the RAS-mitogen-activated protein kinase signalling pathway underlies RASopathies, a family of neurodevelopmental disorders associated with variable cancer predisposition. However, the prevalence and spectrum of solid tumours and the contribution of specific variants to tumour susceptibility remain poorly defined. METHODS: We assessed solid tumour prevalence and spectrum in the largest single-centre cohort of individuals with RASopathies (n=138), excluding neurofibromatosis type 1 and integrated these findings with a systematic literature review to evaluate tumour distribution and genotype-phenotype correlations. RESULTS: In our cohort, at least one solid tumour was identified in 10.8% of individuals with Noonan syndrome (NS), 47.8% with Costello syndrome (CS) and 7.3% with cardiofaciocutaneous syndrome (CFCS). Malignant tumours occurred in 5.4%, 30.4% and 2.4%, respectively. CS showed the highest tumour burden, frequently with multiple primary tumours, predominantly of the bladder. In NS, low-grade central nervous system (CNS) tumours were most common, particularly among individuals carrying PTPN11 variants. Tumour onset occurred with a median age of 19, 14 and 13 years in NS, CS and CFCS, respectively. Literature data analysis identified candidate variants in HRAS, PTPN11 and SOS1 genes associated with increased risk for solid tumours, which differed from mutational hotspots reported in childhood leukaemia or sporadic cancers. CONCLUSION: Solid tumour risk in RASopathies is syndrome-dependent and genotype-dependent, with CS showing a high burden of bladder tumours and NS mainly associated with CNS tumours. These findings may support tailored surveillance strategies.

INTRODUCTION: Cardiofaciocutaneous (CFC) syndrome is a rare RASopathy caused predominantly by germline BRAF variants; functional gastrointestinal symptoms are common, but structural gastrointestinal malformations are exceptional. CASE PRESENTATION: We report a 10-month-old male with a de novo BRAF (NM_004333.6):c.1914T>A, p.(Asp638Glu) pathogenic variant who presented neonatally with a duodenal duplication cyst causing partial pyloric obstruction and underwent surgical excision at 3.5 months. To our knowledge, no previous duodenal duplication cyst has been reported in CFC syndrome or in any other RASopathy in the indexed literature. CONCLUSION: RAS/MAPK signalling regulates foregut recanalisation, raising the possibility of a mechanistic link, although causality cannot be established from a single observation. This hypothesis-generating case may expand the reported gastrointestinal phenotype of RASopathies; structural imaging may be considered in CFC patients with obstructive vomiting disproportionate to expected functional feeding difficulties.

This piece highlights the experience of a caregiver of a young person with cardiofaciocutaneous syndrome diagnosed with melanoma in situ. While the amount of scientific research on genodermatoses has increased since this patient's diagnosis, very little exploration of the patient and family experience exists in the literature. This manuscript, based on in-depth discussions with the patient's caregiver, underscores the importance of the physician-patient relationship, specifically in rare disorders. While ultraspecialized care is undoubtedly important, this narrative argues that contextual knowledge and longstanding relationships can be equally impactful in delivering effective and compassionate care.

RASopathies comprise a group of congenital malformation syndromes with predominant neuro-cardio-facial-cutaneous involvement resulting from pathogenic variants in RAS/mitogen-activated protein kinase (MAPK) signaling pathway genes. In this study 33 patients are presented with their clinical and molecular findings as an RASopathy cohort including a family with an AMMECR1-related disorder. The diagnostic distribution of the cohort included Noonan syndrome (n = 18), neurofibromatosis type 1 (n = 8), and single cases of cardiofaciocutaneous syndrome, Costello syndrome, neurofibromatosis-Noonan syndrome, NF1 microdeletion syndrome, Noonan syndrome-like disorder with loose anagen hair, Noonan syndrome with multiple lentigines and AMMECR1-related midface hypoplasia, hearing impairment, elliptocytosis, and nephrocalcinosis (MIM# 300990). The most prevalent clinical manifestations were dermatological findings (90.9%), skeletal features (84.4%), cardiovascular involvement (75.8%), and typical craniofacial dysmorphism suggestive of RASopathy (72.7%). Variants were most frequently identified in PTPN11 and NF1, followed by single cases involving the BRAF, HRAS, LZTR1, RAF1, RIT1, SHOC2, and SOS1. Notably, one patient harbored a variant in AMMECR1, which is not involved in the RAS/MAPK pathway. Overall, this study delineates the clinical and molecular landscape of a cohort from Türkiye and underscores that the AMMECR1-related phenotype represents a distinct entity that closely mimics Noonan syndrome.

RASopathies are a group of developmental disorders caused by variations in genes of the RAS/mitogen activated protein kinase (MAPK) pathway and affect 1 in 1000 individuals worldwide. Due to overlapping clinical features, accurate diagnosis is challenging and therefore we used next-generation sequencing (NGS) panels as an effective molecular diagnostic tool. Targeted sequencing was performed on 130 samples using a multigene panel comprising of 21 RASopathy genes. Molecular analysis revealed variations in 74 individuals (57%). Pathogenic or likely pathogenic variations were observed in 60/74 (81%) of the cases, 13 (17.5%) had variant(s) of uncertain significance (VUS), and one novel variant was identified in RASA2 whose pathogenicity has not yet been established. In individuals with Noonan Syndrome, pathogenic variants were identified in eight different genes mainly PTPN11, SOS1, RAF1 and LZTR1. Nine clinically diagnosed Cardio-facio-cutaneous syndrome cases harboured variations in BRAF, MAP2K2 and MAP2K1 The c.34G>A variant in HRAS was seen in all nine individuals diagnosed with Costello syndrome. This study provides a comprehensive molecular and clinical profile of the largest Indian RASopathy cohort. The use of targeted gene panel has increased the variation detection rate in affected individuals.