The activation of this pathway during development results in patients with these four disorders exhibiting overlapping phenotypes: Noonan syndrome and NF1 are both associated with freckling/café au lait spots, and occasionally multiple GCG of the jaw, in addition to dysmorphic craniofacial features, congenital cardiac defects, skin abnormalities, varying degrees of intellectual disability, and increased risk of malignancies (acute leukemia). Here, NF1 is linked to Noonan syndrome.