The c.275T>G variant in the MAP2K1 gene is a missense variant predicted to cause substitution of leucine by arginine at amino acid 92 (p.Leu92Arg). This variant is absent from gnomAD v4.1.0 (PM2_Supporting). The computational predictor REVEL gives a score of 0.793 (PP3). The variant is located in the MAP2K1 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). This variant has been reported in 4 independent patients with clinical feature of a RASopathy, 1 as a confirmed de novo occurrence and 2 as unconfirmed de novo occurrences (PS4_Moderate, PM6_VeryStrong; GeneDx, APHP-Robert Debré hospital, Laboratory for Molecular Medicine internal data; ClinVar SCV000207940.11, SCV000965969.1, SCV000061251.5, PMID: 35524774). In summary, this variant meets criteria to be classified as pathogenic for autosomal dominant RASopathies based on ACMG/AMP criteria applied, as specified by the ClinGen RASopathy Variant Curation Expert Panel: PM6_VeryStrong, PS4_Moderate, PM2_Supporting, PP2, PP3 (Specification Version 2.1, 09/17/2024)