| Domain | NRAS-specific finding for Noonan syndrome 6 | General Noonan syndrome context | Key citation(s) | Caveats |
|---|---|---|---|---|
| Entity / identifiers | **Noonan syndrome 6** is the **NRAS-associated RASopathy**; Open Targets maps **MONDO:0013186** to **NRAS** with supporting literature including PubMed-linked evidence | General NS is a broader clinical syndrome with multiple RAS/MAPK genes | Open Targets MONDO_0013186→NRAS association (pqac-00000000) | MONDO supported here; OMIM/Orphanet identifiers were not directly retrieved in tool context and should be externally verified before KB ingestion |
| Causal gene & inheritance | **NRAS** heterozygous **germline** variants cause NS6; cohort included **de novo** and **familial** cases with segregation in 4 families; variants confirmed in non-hematopoietic tissues, supporting constitutional origin | NS is usually **autosomal dominant**, with rare recessive exceptions for some non-NRAS genes | Altmüller et al., 2017, *Eur J Hum Genet*, DOI:10.1038/ejhg.2017.65 (pqac-00000020, pqac-00000021); general NS inheritance/prevalence review (pqac-00000026) | Penetrance for NRAS-specific NS6 is not precisely quantified; expressivity is clearly variable |
| Strongest NRAS-specific cohort | Largest directly retrieved NRAS cohort: **19 affected individuals from 13 unrelated families** (9 males, 10 females; median age **7.1 y**, range **3 months–50 y**); majority had clinical NS (**15/19**), with some CFCS/CS overlap | Recent broader NS cohorts are much larger but are **not NRAS-specific** | Altmüller et al., 2017 (pqac-00000020, pqac-00000021) | This remains a small rare-disease cohort; some percentages exclude a complex outlier case from aggregate tables |
| Hallmark phenotype frequencies | Craniofacial/RASopathy-like features in all assessed subjects; **short/webbed neck 94%**, **ocular ptosis 82%**, **cardiac anomalies 59%**, **HCM 35%**, **septal defects 12%**, **pulmonary stenosis 6%**, **motor delay 38%**, **intellectual/learning disabilities 42%**, **prenatal abnormalities 69%** (**polyhydramnios 46%**, **nuchal edema 15%**, **fetal chylothorax/hydrops 23%**), **cryptorchidism 63% of males**, bleeding diathesis **3/15** with one confirmed von Willebrand disease | In broader NS, pulmonary valve stenosis is typically much more common than in NRAS cases; one recent general NS series found cardiac defects **71.5%**, pulmonary valve stenosis **48.3%**, short stature **43.1%** | NRAS cohort frequencies (pqac-00000021, pqac-00000022); broader NS comparison (pqac-00000006, pqac-00000009) | NRAS phenotype can overlap CFCS/Costello-like presentations, especially with Gly12 variants; frequency estimates remain imprecise because of low n |
| Molecular mechanism | Germline activating **NRAS** variants dysregulate **RAS-MAPK** and **PI3K-AKT** signaling. Functional studies showed **NRAS p.Thr58Ile** and **p.Gly12Val** increase **ERK** and **AKT phosphorylation** even without stimulation; p.Thr58Ile shifts protein toward active **GTP-bound** state, though less strongly than oncogenic p.Gly12Val | General NS is a pathway disease of **RAS/MAPK hyperactivation** across multiple genes | Altmüller et al., 2017 mechanistic assays in HEK293T cells (pqac-00000020, pqac-00000018, pqac-00000023) | Mechanistic evidence is strong for selected variants, but not all NS6 variants have equally detailed functional characterization |
| Diagnosis | Best-supported approach is **clinical suspicion of a RASopathy phenotype plus molecular confirmation of an NRAS germline variant**; WES identified at least one atypical/costello-like case, and constitutional status was confirmed in skin fibroblasts, nail keratinocytes, buccal cells, urine, or saliva when needed | General NS diagnosis increasingly relies on multigene **RASopathy panels** / exome sequencing; disease genes include **PTPN11, SOS1, RAF1, RIT1, LZTR1, KRAS, SOS2, NRAS, RRAS, RRAS2, MRAS, SPRED2** | NRAS-specific diagnostic examples (pqac-00000021, pqac-00000023); general NS gene list and diagnostic framing (pqac-00000026) | No NRAS-specific formal clinical criteria were retrieved; differential diagnosis includes other RASopathies, especially CFCS and Costello syndrome |
| Management | No NRAS-specific management guideline was retrieved; current care is extrapolated from **general NS multidisciplinary management** with attention to cardiology, growth, neurodevelopment, feeding, lymphatic issues, and hematologic abnormalities when present | General NS data support genotype-guided care; rGH used in a subset of NS patients and is **not generally contraindicated** when clinically indicated | General NS management summaries (pqac-00000008, pqac-00000006, pqac-00000009) | Evidence for NS6-specific outcome modification is lacking; management remains largely supportive and organ-directed |
| Cancer surveillance | NRAS cohort reported **2 neoplastic/hematologic events**: **JMML-like myeloproliferative disorder** with **p.Gly12Asp** and an uncharacterized **brain tumor/hypothalamic lesion** with **p.Gly12Arg**; authors state more data are needed to define malignancy risk in germline oncogenic NRAS carriers | Updated NS guidance: childhood cancer risk is about **8-fold** above general population, but **routine CBC surveillance is not recommended** for otherwise healthy NS; focus on **clinical exam**, especially hepatosplenomegaly in infancy/early childhood, and family education about tumor symptoms | NRAS-specific tumor observations (pqac-00000019, pqac-00000018, pqac-00000022); general surveillance update 2024 (pqac-00000024, pqac-00000026) | Surveillance recommendations are **general NS**, not validated specifically for NRAS NS6; absolute cancer risk for NS6 remains undefined |
| Active trials / real-world implementation | No active **NRAS-only** interventional trial was retrieved | General NS trials include **NCT05308927** Norditropin registry (observational, enrolling by invitation, est. n=221), **NCT06668805** vosoritide Phase 2 (recruiting, n=30), **NCT06555237** trametinib/MEK inhibitor for RASopathy HCM Phase 2 (recruiting, n=40), plus completed somatropin studies **NCT01529840**, **NCT00452725**, and post-marketing surveillance **NCT03435627** | Trial records (pqac-00000028, pqac-00000029, pqac-00000030, pqac-00000031) | These studies enroll broader NS/RASopathy populations; applicability to NS6 is indirect unless genotype-specific subgroup analyses are reported |


*Table: This table summarizes the highest-yield disease knowledge-base facts for Noonan syndrome 6, emphasizing directly retrieved NRAS-specific evidence and clearly separating it from broader Noonan syndrome data. It is useful as a compact curation aid for identifiers, phenotype, mechanism, surveillance, and currently active clinical studies.*