MAP2K2 p.Phe57Cys

The c.170T>G variant in the MAP2K2 gene is a missense variant predicted to cause substitution of phenylalanine by cysteine at amino acid 57 (p.Phe57Cys). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). The computational predictor REVEL gives a score of 0.959, predicting a damaging impact on protein function (PP3). This variant is in a location that has been defined by the ClinGen RASopathy Expert Panel to be a critical functional domain of MAP2K2 (PM1, AA 47-65). Furthermore, other pathogenic missense variants has been previously identified at this codon of MAP2K2 (Phe57Val, Phe57Ile, Phe57Leu) and in nearby residues in association with CFC syndrome, which may indicate that this residue is critical to the function of the protein (PM5). This variant has been identified in at least 4 patients with RASopathy, of which 1 was an unconfirmed de novo occurrence (PS4_Moderate, PM6; GenomeConnect, ClinVar: SCV002047662.1; PMID: 16439621, 18039235, 21062266). ERK phosphorylation assays showed that this variant led to increased phosphorylation compared to wild-type (PS3_Supporting; PMID: 16439621, 17981815). In summary, this variant meets criteria to be classified as pathogenic for autosomal dominant RASopathies based on the ACMG/AMP criteria applied, as specified by the ClinGen RASopathy Variant Curation Expert Panel: PS4_Moderate, PM1, PM5, PM6, PS3_Supporting, PM2_Supporting, PP3 (Specification Version 2.3, 12/3/2024)