Noonan and LEOPARD syndromes are developmental disorders with overlapping features, including cardiac abnormalities, short stature and facial dysmorphia. Increased RAS signaling owing to PTPN11, SOS1 and KRAS mutations causes 60% of Noonan syndrome cases1,2,3,4,5,6, and PTPN11 mutations cause 90% of LEOPARD syndrome cases7. Here, we report that 18 of 231 individuals with Noonan syndrome without known mutations (corresponding to 3% of all affected individuals) and two of six individuals with LEOPARD syndrome without PTPN11 mutations have missense mutations in RAF1, which encodes a serine-threonine kinase that activates MEK1 and MEK2. Most mutations altered a motif flanking Ser259, a residue critical for autoinhibition of RAF1 through 14-3-3 binding. Of 19 subjects with a RAF1 mutation in two hotspots, 18 (or 95%) showed hypertrophic cardiomyopathy (HCM), compared with the 18% prevalence of HCM among individuals with Noonan syndrome in general. Ectopically expressed RAF1 mutants from the two HCM hotspots had increased kinase activity and enhanced ERK activation, whereas non–HCM-associated mutants were kinase impaired. Our findings further implicate increased RAS signaling in pathological cardiomyocyte hypertrophy.

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We are indebted to the affected individuals and families who participated in the study, the physicians who referred the subjects and the Joint Genome Institute's production sequencing group. We thank D.K. Morrison (National Cancer Institute, US National Institutes of Health) for critical reagents and suggestions. We also thank G. Crisponi (Clinica Sant'Anna, Cagliari, Italy), F. Faravelli (Ospedale Galliera, Genova, Italy), L. Memo (ULLS9, Treviso, Italy) and F. Stanzial (Regional Hospital, Bolzano, Italy) for their valuable clinical assistance. This work was supported by Telethon-Italy grant GGP07115 (M.T.) and Programma di Collaborazione Italia-USA/malattie rare 2007 grants (M.T. and A.S.); US National Institutes of Health Grants HL71207, HD01294, HL074728 (B.D.G.), HD042569 (M.J.A.) and DK57683 (P.M.); the American Heart Association (M.J.A.); the Dr. Scholl Foundation (M.J.A.); the CJ Foundation for SIDS and the Mayo Foundation (M.J.A.) and Italian Ministry of Health Grant RC 2006-2007, Italian Ministry of University and Research C26A06KTTN and RBIP06PMF2_005 (B.D.). Research conducted at the E.O. Lawrence Berkeley National Laboratory and the Joint Genome Institute was performed under the Berkeley Program for Genomic Applications, funded by the US National Heart, Lung and Blood Institute (HL066681) and Department of Energy Contract DE-AC02-05CH11231 (University of California). We regret our inability to cite certain references describing work similar to references that were cited due to the limits of this journal.

Author information

Author notes

    • Marco Tartaglia
    •  & Bruce D Gelb

    These authors contributed equally to this work.


  1. Center for Molecular Cardiology, Department of Pediatrics and Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, New York 10029, USA.

    • Bhaswati Pandit
    • , Kimihiko Oishi
    • , Marco Tartaglia
    •  & Bruce D Gelb
  2. Istituto di Ricovero e Cura a Carattere Scientifico-Casa Sollievo della Sofferenza (CSS), San Giovanni Rotondo and CSS-Mendel Institute, Viale Regina Elena 261, 00198 Rome, Italy.

    • Anna Sarkozy
    • , Giorgia Esposito
    • , Francesca Lepri
    • , Isabella Torrente
    •  & Bruno Dallapiccola
  3. Department of Experimental Medicine, University La Sapienza, Viale Regina Elena 261, 00198 Rome, Italy.

    • Anna Sarkozy
    • , Giorgia Esposito
    • , Francesca Lepri
    •  & Bruno Dallapiccola
  4. Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

    • Len A Pennacchio
    • , Wendy Schackwitz
    •  & Anna Ustaszewska
  5. US Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, California 94598, USA.

    • Len A Pennacchio
    •  & Wendy Schackwitz
  6. Dipartimento di Biologia Cellulare e Neuroscienze, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.

    • Claudio Carta
    • , Simone Martinelli
    • , Edgar A Pogna
    •  & Marco Tartaglia
  7. Departments of Medicine, Pediatrics and Molecular Pharmacology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.

    • Andrew Landstrom
    • , J Martijn Bos
    • , Steve R Ommen
    •  & Michael J Ackerman
  8. Department of Medicine, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, New York 10029, USA.

    • Christian Faul
    •  & Peter Mundel
  9. Endocrinología Pediátrica, Hospital Materno-Infantil, Avida Arroyo de los Ángeles, 29011 Málaga, Spain.

    • Juan P López Siguero
  10. Departimento di Pediatria, Università di Padova, Via Giustiniani 3, 35128 Padua, Italy.

    • Romano Tenconi
  11. Clinica Pediatrica, Università di Milano, Via della Commenda 9, 20122 Milano, Italy.

    • Angelo Selicorni
  12. Dipartmento di Pediatria, Policlinico S. Orsola-Malpighi, Università di Bologna, Via Massarenti 9, 40138 Bologna, Italy.

    • Cesare Rossi
    •  & Laura Mazzanti
  13. Dipartimento di Pediatria, Policlinico Umberto I, Università di Roma La Sapienza, Viale Regina Elena 324, 00161 Rome, Italy.

    • Bruno Marino
  14. Genetica Medica, Ospedale Bambino Gesù, Piazza S. Onofrio 4, 00165 Rome, Italy.

    • Maria C Digilio
  15. Istituto di Clinica Pediatrica, Università Cattolica del Sacro Cuore, Largo A. Gemelli 8, 00168 Rome, Italy.

    • Giuseppe Zampino


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Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Marco Tartaglia or Bruce D Gelb.

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