Only one case has been identified that had Costello syndrome-like features and a variant in the SOS1 gene (Tumurkhuu et al., 2010). This patient was described to have a phenotype between CS and cardiofaciocutaneous syndrome, that was more similar to CS, but the authors noted that there were no differentiating features to support diagnosis. Additionally, there is no further evidence to support the variant’s impact, so the association has been classified as Disputed. The HRAS gene is believed to be the only gene associated with CS (Aoki et al., 2005; Estep, Tidyman, Teitell, Cotter, & Rauen, 2006; Gripp et al., 2006; Kerr et al., 2006; Zampino et al., 2007). Of note, SOS1 has also been classified as definitive in association with Noonan syndrome (NS) and as disputed in association with CFC syndrome. The ClinGen RASopathy Gene Curation Expert Panel found no evidence associating SOS1 with either NS with loose anagen hair or NS with multiple lentigines. This curation was approved by the ClinGen RASopathy Gene Curation Expert Panel on 7/24/18 (SOP Version 5).
The GenCC data are available free of restriction under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication. The GenCC requests that you give attribution to GenCC and the contributing sources whenever possible and appropriate. The accepted Flagship manuscript is now available from Genetics in Medicine (https://www.gimjournal.org/article/S1098-3600(22)00746-8/fulltext).
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