Two cases of RIT1 associated Noonan syndrome: Further delineation of the clinical phenotype and review of the literature

Am J Med Genet A. 2016 Jul;170(7):1874-80. doi: 10.1002/ajmg.a.37657. Epub 2016 Apr 25.


Mutations in RIT1, involved in the RAS-MAPK pathway, have recently been identified as a cause for Noonan syndrome. We present two patients with Noonan syndrome caused by a RIT1 mutation with novel phenotypic manifestations, severe bilateral lower limb lymphedema starting during puberty, and fetal hydrops resulting in intrauterine fetal death, respectively. Including our patients, a total of 52 patients have been reported with Noonan syndrome caused by a RIT1 mutation. Our report contributes to the delineation of the phenotype associated with RIT1 mutations and underlines that lymphatic involvement is part of this spectrum. In addition, we provide an overview of the currently described Noonan syndrome patients with RIT1 mutations in literature. © 2016 Wiley Periodicals, Inc.

Keywords: Noonan syndrome; RASopathy; RIT1; hydrops fetalis; lymphedema.

MeSH terms

  • Female
  • Humans
  • Hydrops Fetalis / genetics*
  • Hydrops Fetalis / physiopathology
  • Lower Extremity / physiopathology
  • Male
  • Mutation, Missense
  • Noonan Syndrome / genetics*
  • Noonan Syndrome / physiopathology
  • Phenotype
  • ras Proteins / genetics*


  • RIT1 protein, human
  • ras Proteins