KRAS gene mutations in Noonan syndrome familial cases cluster in the vicinity of the switch II region of the G-domain: Report of another family with metopic craniosynostosis

Author(s)

Brasil, Amanda S. ^[1] ; Malaquias, Alexsandra C. ^[2] ; Kim, Chong A. ^[1] ; Krieger, Jose Eduardo ^[3] ; Jorge, Alexander A. L. ^[4] ; Pereira, Alexandre C. ^[3] ; Bertola, Debora R. ^[1]

Affiliation

^[1] HC FMUSP, Inst Crianca, Unidade Genet, Sao Paulo - Brazil

^[2] HC FMUSP, Lab Hormonios & Genet Mol, LIM 42, Unidade Endocrinol Desenvolvimento, Sao Paulo - Brazil

^[3] HC FMUSP, InCor, Lab Genet & Cardiol Mol, Sao Paulo - Brazil

^[4] Univ Sao Paulo, Fac Med, Unidade Endocrinol Genet LIM 25, Disciplina Endocrinol, HC FMUSP, Sao Paulo - Brazil

• Document type: Journal article
• Source: AMERICAN JOURNAL OF MEDICAL GENETICS PART A; v. 158A, n. 5, p. 1178-1184, MAY 2012.
• Web of Science Citations: 7

Abstract

Noonan syndrome (NS) and Noonan-related disorders {[}cardio-facio-cutaneous (CFC), Costello, Noonan syndrome with multiple lentigines (NS-ML), and neurofibromatosis-Noonan syndromes (NFNS)] are a group of developmental disorders caused by mutations in genes of the RAS/MAPK pathway. Mutations in the KRAS gene account for only a small proportion of affected Noonan and CFC syndrome patients that present an intermediate phenotype between these two syndromes, with more frequent and severe intellectual disability in NS and less ectodermal involvement in CFC syndrome, as well as atypical clinical findings such as craniosynostosis. Recently, the first familial case with a novel KRAS mutation was described. We report on a second vertical transmission (a mother and two siblings) with a novel mutation (p.M72L), in which the proband has trigonocephaly and the affected mother and sister, prominent ectodermal involvement. Metopic suture involvement has not been described before, expanding the main different cranial sutures which can be affected in NS and KRAS gene mutations. The gene alteration found in the studied family is in close proximity to the one reported in the other familial case (close to the switch II region of the G-domain), suggesting that this specific region of the gene could have less severe effects on intellectual ability than the other KRAS gene mutations found in NS patients and be less likely to hamper reproductive fitness. (c) 2012 Wiley Periodicals, Inc. (AU)