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

Authors

  • Amanda S. Brasil,

    Corresponding author
    1. Unidade de Genética, Instituto da Criança, HC/FMUSP, São Paulo, SP, Brazil
    • Amanda S. Brasil, Av. Dr. Enéas de Carvalho Aguiar, 647, Cerqueira César, 05403-900 São Paulo, SP, Brasil.

      Débora R. Bertola, Av. Dr. Enéas de Carvalho Aguiar, 647, Cerqueira César, 05403-900 São Paulo, SP, Brazil.

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  • Alexsandra C. Malaquias,

    1. Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular, LIM/42, HC/FMUSP, São Paulo, SP, Brazil
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  • Chong A. Kim,

    1. Unidade de Genética, Instituto da Criança, HC/FMUSP, São Paulo, SP, Brazil
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  • José Eduardo Krieger,

    1. Laboratório de Genética e Cardiologia Molecular, InCor, HC/FMUSP, São Paulo, SP, Brazil
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  • Alexander A.L. Jorge,

    1. Unidade de Endocrinologia-Genética – LIM/25, Disciplina de Endocrinologia da Faculdade de Medicina da Universidade de São Paulo, HC/FMUSP, São Paulo, SP, Brazil
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  • Alexandre C. Pereira,

    1. Laboratório de Genética e Cardiologia Molecular, InCor, HC/FMUSP, São Paulo, SP, Brazil
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  • Débora R. Bertola

    Corresponding author
    1. Unidade de Genética, Instituto da Criança, HC/FMUSP, São Paulo, SP, Brazil
    • Amanda S. Brasil, Av. Dr. Enéas de Carvalho Aguiar, 647, Cerqueira César, 05403-900 São Paulo, SP, Brasil.

      Débora R. Bertola, Av. Dr. Enéas de Carvalho Aguiar, 647, Cerqueira César, 05403-900 São Paulo, SP, Brazil.

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  • How to Cite this Article: Brasil AS, Malaquias AC, Kim CA, Krieger JE, Jorge AAL, Pereira AC, Bertola DR. 2012. 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. Am J Med Genet Part A. 158A:1178–1184.

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. © 2012 Wiley Periodicals, Inc.

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