NRAS and congenital mesoblastic nephroma: Extracutaneous associations described thus far are characteristic facial features,1 and a wide range of neurological abnormalities detectable on magnetic resonance imaging (MRI),2, 3 seen in approximately 20% of children with more than one CMN at birth.4 Molecular studies have established that approximately 80% of cases of multiple CMN or CMN syndrome are caused by mosaicism for oncogenic mutations in codon 61 of NRAS,5 classifying the majority as a mosaic RASopathy.