The filtering allele frequency of the c.848C>T (p.Ala283Val) variant in the MAP2K1 gene is 0.052% for African chromosomes by the Exome Aggregation Consortium (10/10366 with 95% CI), which is a high enough frequency to be classified as benign based on thresholds defined by the ClinGen RASopathy Expert panel for autosomal dominant RASopathy variants (BA1). This variant has been identified in a patient with an alternate molecular basis for disease (BP5; Partners LMM, GeneDx internal data; GTR ID: 21766, 26957; ClinVar SCV000207935.12; SCV000061262.5). In summary, this variant meets criteria to be classified as benign. RASopathy-specific ACMG/AMP criteria applied (PMID:29493581): BA1, BP5.