The c.169A>C (p.Lys57Gln) variant in MAP2K1 was absent from large population studies (PM2; gnomAD.broadinstitute.org). It has been reported in 3 total patients with clinical features of a RASopathy (PS4_Moderate; SCV000061249.5; Otto von Guericke University Magdeburg internal data; Invitae internal data). One was a confirmed de novo occurrence and one was an unconfirmed de novo occurrence (PS2; PM6; SCV000061249.5; Otto von Guericke University Magdeburg internal data). The p.Lys57Gln variant is located in the negative regulatory region, which has been defined by the ClinGen RASopathy Expert Panel to be a mutational hotspot or domain of MAP2K1 (PM1; PMID 29493581). Computational prediction tools and conservation analysis suggest that the p.Lys57Gln variant may impact the protein (PP3). Furthermore, the variant is located in MAP2K1, which has been defined by the ClinGen RASopathy Expert Panel as a gene with a low rate of benign missense variants and pathogenic variants are common (PP2; PMID: 29493581). In summary, this variant meets criteria to be classified as pathogenic for RASopathies in an autosomal dominant manner. Rasopathy-specific ACMG/AMP criteria applied (PMID:29493581): PS2, PS4_Moderate, PM2, PM6, PM1, PP3, PP2.