Noonan phenotype associated with neurofibromatosis.

We report on four patients with neurofibromatosis and manifestations of Noonan syndrome including short stature, ptosis, "midface hypoplasia," apparently short webbed neck, learning disabilities, and weakness. No family history of neurofibromatosis was present in any case. Average paternal and maternal age at birth was 37 and 28 years, respectively, suggestive of a new mutation. The presence of a distinct phenotype and hypotonia in these patients with neurofibromatosis is suggestive of a new separate disorder.