The c.400T>C (p.Tyr134His) variant in MAP2K2 was absent from large population studies (PM2). It has been identified in 3 patients with Cardiofaciocutaneous syndrome and 1 with Noonan syndrome (PS4_Moderate; SCV000063166.5, Hopital Universitaire Robert Debre internal data, PMIDs: 18042262, 27763634) Furthermore, the variant is in a location that has been defined by the ClinGen RASopathy Expert Panel to be a mutational hotspot or domain of MAP2K2 (PM1; PMID 29493581). Moreover, a different pathogenic missense variant (p.Tyr134Cys) has been previously identified at this codon of MAP2K2 which may indicate that this residue is critical to the function of the protein (PM5 not met; ClinVar 177868). The variant is located in the MAP2K2 gene, which has been defined by the ClinGen RASopathy Expert Panel as a gene with a low rate of benign missense variants and pathogenic missense variants are common (PP2; PMID 29493581). Computational prediction tools and conservation analysis suggest that the p.Tyr134His variant may impact the protein (PP3). In summary, this variant meets criteria to be classified as likely pathogenic for RASopathies in an autosomal dominant manner. RASopathy-specific ACMG/AMP criteria applied (PMID:29493581): PM2, PS4_Moderate, PM1, PP2, PP3.