In the present series of patients from one family, all patients carry the same recurrent mutation Y279C in the PTPN11 gene, exhibiting different phenotypes and a variable expression of multiple lentigines.
We hypothesise that some PTPN11 mutations are associated with the typical Noonan syndrome phenotype and that other mutations, such as the Y279C mutation reported here, are associated with both the Noonan syndrome phenotype and with skin pigmentation anomalies, such as multiple lentigines or café au lait spots.