DHPLC mutation scanning of coding exons, splice junctions, and flanking intronic portions of SOS1 did not reveal any putative pathogenic mutation in the nine subjects with a diagnosis of CFCS and negative for mutations in BRAF, KRAS, MAP2K1, and MAP2K2. Similarly, no mutation was identified among the 59 patients with nonsyndromic CHDs included in the study, excluding a major involvement of germline SOS1 mutations in PS (N = 21; 95% confidence interval [CI] = 0.000–0.192), ASD (N = 23, 95% CI = 0.000–0.178), and VSD (N = 15, 95% CI = 0.000–0.253). Here, MAP2K1 is linked to cardiofaciocutaneous syndrome 1.