Human Genetics

, Volume 138, Issue 6, pp 625–634 | Cite as

Biallelic variants in SMAD6 are associated with a complex cardiovascular phenotype

  • Katja Kloth
  • Tatjana Bierhals
  • Jessika Johannsen
  • Frederike L. Harms
  • Jane Juusola
  • Mark C. Johnson
  • Dorothy K. Grange
  • Kerstin KutscheEmail author
Original investigation


Rare heterozygous variants in SMAD6 have been identified as a significant genetic contributor to bicuspid aortic valve-associated thoracic aortic aneurysm on one hand and non-syndromic midline craniosynostosis on the other. In this study, we report two individuals with biallelic missense variants in SMAD6 and a complex cardiac phenotype. Trio exome sequencing in Proband 1, a male who had aortic isthmus stenosis, revealed the homozygous SMAD6 variant p.(Ile466Thr). He also had mild intellectual disability and radio-ulnar synostosis. Proband 2 is a female who presented with a more severe cardiac phenotype with a dysplastic and stenotic pulmonary valve and dilated cardiomyopathy. In addition, she had vascular anomalies, including a stenotic left main coronary artery requiring a bypass procedure, narrowing of the proximal left pulmonary artery and a venous anomaly in the brain. Proband 2 has compound heterozygous SMAD6 missense variants, p.(Phe357Ile) and p.(Ser483Pro). Absence of these SMAD6 variants in the general population and high pathogenicity prediction scores suggest that these variants caused the probands’ phenotypes. This is further corroborated by cardiovascular anomalies and appendicular skeletal defects in Smad6-deficient mice. SMAD6 acts as an inhibitory SMAD and preferentially inhibits bone morphogenetic protein (BMP)-induced signaling. Our data suggest that biallelic variants in SMAD6 may affect the inhibitory activity of SMAD6 and cause enhanced BMP signaling underlying the cardiovascular anomalies and possibly other clinical features in the two probands.



We thank the two probands and family members for their participation in this study and Inka Jantke for skillful technical assistance.


This work was supported by a grant from the Deutsche Forschungsgemeinschaft (KU 1240/10-1 to Ke.K.).

Compliance with ethical standards

Conflict of interest

J.J. is an employee of GeneDx, Inc. All other authors declare no competing interests.

Supplementary material

439_2019_2011_MOESM1_ESM.docx (100 kb)
Supplementary material 1 (DOCX 100 kb)


  1. Bai S, Cao X (2002) A nuclear antagonistic mechanism of inhibitory Smads in transforming growth factor-beta signaling. J Biol Chem 277:4176–4182. CrossRefPubMedGoogle Scholar
  2. Bai S, Shi X, Yang X, Cao X (2000) Smad6 as a transcriptional corepressor. J Biol Chem 275:8267–8270CrossRefPubMedGoogle Scholar
  3. Braverman AC, Guven H, Beardslee MA, Makan M, Kates AM, Moon MR (2005) The bicuspid aortic valve. Curr Probl Cardiol 30:470–522. CrossRefPubMedGoogle Scholar
  4. Cai J, Pardali E, Sanchez-Duffhues G, ten Dijke P (2012) BMP signaling in vascular diseases. FEBS Lett 586:1993–2002. CrossRefPubMedGoogle Scholar
  5. Cannaerts E, van de Beek G, Verstraeten A, Van Laer L, Loeys B (2015) TGF-beta signalopathies as a paradigm for translational medicine. Eur J Med Genet 58:695–703. CrossRefGoogle Scholar
  6. Estrada KD, Retting KN, Chin AM, Lyons KM (2011) Smad6 is essential to limit BMP signaling during cartilage development. J Bone Miner Res 26:2498–2510. CrossRefPubMedPubMedCentralGoogle Scholar
  7. Friedman T, Mani A, Elefteriades JA (2008) Bicuspid aortic valve: clinical approach and scientific review of a common clinical entity. Expert Rev Cardiovasc Ther 6:235–248. CrossRefPubMedGoogle Scholar
  8. Galvin KM, Donovan MJ, Lynch CA, Meyer RI, Paul RJ, Lorenz JN, Fairchild-Huntress V, Dixon KL, Dunmore JH, Gimbrone MA Jr, Falb D, Huszar D (2000) A role for smad6 in development and homeostasis of the cardiovascular system. Nat Genet 24:171–174. CrossRefPubMedPubMedCentralGoogle Scholar
  9. Garg V, Muth AN, Ransom JF, Schluterman MK, Barnes R, King IN, Grossfeld PD, Srivastava D (2005) Mutations in NOTCH1 cause aortic valve disease. Nature 437:270–274. CrossRefPubMedPubMedCentralGoogle Scholar
  10. Garza RM, Khosla RK (2012) Nonsyndromic craniosynostosis. Semin Plast Surg 26:53–63. CrossRefPubMedPubMedCentralGoogle Scholar
  11. Gillis E, Kumar AA, Luyckx I, Preuss C, Cannaerts E, van de Beek G, Wieschendorf B, Alaerts M, Bolar N, Vandeweyer G, Meester J, Wunnemann F, Gould RA, Zhurayev R, Zerbino D, Mohamed SA, Mital S, Mertens L, Bjorck HM, Franco-Cereceda A, McCallion AS, Van Laer L, Verhagen JMA, van de Laar I, Wessels MW, Messas E, Goudot G, Nemcikova M, Krebsova A, Kempers M, Salemink S, Duijnhouwer T, Jeunemaitre X, Albuisson J, Eriksson P, Andelfinger G, Dietz HC, Verstraeten A, Loeys BL, Mibava Leducq C (2017) Candidate gene resequencing in a large bicuspid aortic valve-associated thoracic aortic aneurysm cohort: SMAD6 as an important contributor. Front Physiol 8:400. CrossRefPubMedPubMedCentralGoogle Scholar
  12. Girdauskas E, Borger MA (2013) Bicuspid aortic valve and associated aortopathy: an update. Semin Thorac Cardiovasc Surg 25:310–316. CrossRefPubMedGoogle Scholar
  13. Gomez-Puerto MC, Iyengar PV, Garcia de Vinuesa A, Ten Dijke P, Sanchez-Duffhues G (2019) Bone morphogenetic protein receptor signal transduction in human disease. J Pathol 247:9–20. CrossRefPubMedGoogle Scholar
  14. Goto K, Kamiya Y, Imamura T, Miyazono K, Miyazawa K (2007) Selective inhibitory effects of Smad6 on bone morphogenetic protein type I receptors. J Biol Chem 282:20603–20611. CrossRefPubMedGoogle Scholar
  15. Goumans MJ, Zwijsen A, Ten Dijke P, Bailly S (2018) Bone morphogenetic proteins in vascular homeostasis and disease. Cold Spring Harb Perspect Biol 10:a031989. CrossRefPubMedGoogle Scholar
  16. Guo DC, Gong L, Regalado ES, Santos-Cortez RL, Zhao R, Cai B, Veeraraghavan S, Prakash SK, Johnson RJ, Muilenburg A, Willing M, Jondeau G, Boileau C, Pannu H, Moran R, Debacker J, Bamshad MJ, Shendure J, Nickerson DA, Leal SM, Raman CS, Swindell EC, Milewicz DM, GenTac Investigators NHL, Blood Institute Go Exome Sequencing P, Montalcino Aortic C (2015) MAT2A mutations predispose individuals to thoracic aortic aneurysms. Am J Hum Genet 96:170–177. CrossRefPubMedPubMedCentralGoogle Scholar
  17. Hanyu A, Ishidou Y, Ebisawa T, Shimanuki T, Imamura T, Miyazono K (2001) The N domain of Smad7 is essential for specific inhibition of transforming growth factor-beta signaling. J Cell Biol 155:1017–1027. CrossRefPubMedPubMedCentralGoogle Scholar
  18. Harms FL, Kloth K, Bley A, Denecke J, Santer R, Lessel D, Hempel M, Kutsche K (2018) Activating mutations in PAK1, encoding p21-activated kinase 1, cause a neurodevelopmental disorder. Am J Hum Genet 103:579–591. CrossRefPubMedPubMedCentralGoogle Scholar
  19. Hempel M, Cremer K, Ockeloen CW, Lichtenbelt KD, Herkert JC, Denecke J, Haack TB, Zink AM, Becker J, Wohlleber E, Johannsen J, Alhaddad B, Pfundt R, Fuchs S, Wieczorek D, Strom TM, van Gassen KL, Kleefstra T, Kubisch C, Engels H, Lessel D (2015) De novo mutations in CHAMP1 cause intellectual disability with severe speech impairment. Am J Hum Genet 97:493–500. CrossRefPubMedPubMedCentralGoogle Scholar
  20. Hinton RB (2012) Bicuspid aortic valve and thoracic aortic aneurysm: three patient populations, two disease phenotypes, and one shared genotype. Cardiol Res Pract 2012:926975. CrossRefPubMedPubMedCentralGoogle Scholar
  21. Horiki M, Imamura T, Okamoto M, Hayashi M, Murai J, Myoui A, Ochi T, Miyazono K, Yoshikawa H, Tsumaki N (2004) Smad6/Smurf1 overexpression in cartilage delays chondrocyte hypertrophy and causes dwarfism with osteopenia. J Cell Biol 165:433–445. CrossRefPubMedPubMedCentralGoogle Scholar
  22. Ioannidis NM, Rothstein JH, Pejaver V, Middha S, McDonnell SK, Baheti S, Musolf A, Li Q, Holzinger E, Karyadi D, Cannon-Albright LA, Teerlink CC, Stanford JL, Isaacs WB, Xu JF, Cooney KA, Lange EM, Schleutker J, Carpten JD, Powell IJ, Cussenot O, Cancel-Tassin G, Giles GG, MacInnis RJ, Maier C, Hsieh CL, Wiklund F, Catalona WJ, Foulkes WD, Mandal D, Eeles RA, Kote-Jarai Z, Bustamante CD, Schaid DJ, Hastie T, Ostrander EA, Bailey-Wilson JE, Radivojac P, Thibodeau SN, Whittemore AS, Sieh W (2016) REVEL: an ensemble method for predicting the pathogenicity of rare missense variants. Am J Hum Genet 99:877–885. CrossRefPubMedPubMedCentralGoogle Scholar
  23. Jagadeesh KA, Wenger AM, Berger MJ, Guturu H, Stenson PD, Cooper DN, Bernstein JA, Bejerano G (2016) M-CAP eliminates a majority of variants of uncertain significance in clinical exomes at high sensitivity. Nat Genet 48:1581–1586. CrossRefPubMedGoogle Scholar
  24. Kajdic N, Spazzapan P, Velnar T (2018) Craniosynostosis—recognition, clinical characteristics, and treatment. Bosn J Basic Med Sci 18:110–116. CrossRefPubMedPubMedCentralGoogle Scholar
  25. Kamiya Y, Miyazono K, Miyazawa K (2010) Smad7 inhibits transforming growth factor-beta family type i receptors through two distinct modes of interaction. J Biol Chem 285:30804–30813. CrossRefPubMedPubMedCentralGoogle Scholar
  26. Kircher M, Witten DM, Jain P, O’Roak BJ, Cooper GM, Shendure J (2014) A general framework for estimating the relative pathogenicity of human genetic variants. Nat Genet 46:310–315. CrossRefPubMedPubMedCentralGoogle Scholar
  27. Kruithof BP, Duim SN, Moerkamp AT, Goumans MJ (2012) TGFbeta and BMP signaling in cardiac cushion formation: lessons from mice and chicken. Differentiation 84:89–102. CrossRefPubMedGoogle Scholar
  28. Lewin MB, Otto CM (2005) The bicuspid aortic valve: adverse outcomes from infancy to old age. Circulation 111:832–834. CrossRefPubMedGoogle Scholar
  29. Lin X, Liang YY, Sun B, Liang M, Shi Y, Brunicardi FC, Shi Y, Feng XH (2003) Smad6 recruits transcription corepressor CtBP to repress bone morphogenetic protein-induced transcription. Mol Cell Biol 23:9081–9093CrossRefPubMedPubMedCentralGoogle Scholar
  30. Lo RS, Chen YG, Shi Y, Pavletich NP, Massague J (1998) The L3 loop: a structural motif determining specific interactions between SMAD proteins and TGF-beta receptors. EMBO J 17:996–1005. CrossRefPubMedPubMedCentralGoogle Scholar
  31. Loeys BL, Dietz HC (1993) Loeys-Dietz syndrome. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A (eds) Gene reviews®. University of Washington, SeattleGoogle Scholar
  32. Malcic I, Grgat J, Kniewald H, Saric D, Dilber D, Bartonicek D (2015) Bicuspid aortic valve and left ventricular outflow tract defects in children—syndrome of bicuspid aortopathy? Lijec Vjesn 137:267–275PubMedGoogle Scholar
  33. Miyazawa K, Miyazono K (2017) Regulation of TGF-beta family signaling by inhibitory smads. Cold Spring Harb Perspect Biol 9:a022095. CrossRefPubMedPubMedCentralGoogle Scholar
  34. Rauch A, Wieczorek D, Graf E, Wieland T, Endele S, Schwarzmayr T, Albrecht B, Bartholdi D, Beygo J, Di Donato N, Dufke A, Cremer K, Hempel M, Horn D, Hoyer J, Joset P, Ropke A, Moog U, Riess A, Thiel CT, Tzschach A, Wiesener A, Wohlleber E, Zweier C, Ekici AB, Zink AM, Rump A, Meisinger C, Grallert H, Sticht H, Schenck A, Engels H, Rappold G, Schrock E, Wieacker P, Riess O, Meitinger T, Reis A, Strom TM (2012) Range of genetic mutations associated with severe non-syndromic sporadic intellectual disability: an exome sequencing study. Lancet 380:1674–1682. CrossRefPubMedGoogle Scholar
  35. Retterer K, Juusola J, Cho MT, Vitazka P, Millan F, Gibellini F, Vertino-Bell A, Smaoui N, Neidich J, Monaghan KG, McKnight D, Bai R, Suchy S, Friedman B, Tahiliani J, Pineda-Alvarez D, Richard G, Brandt T, Haverfield E, Chung WK, Bale S (2016) Clinical application of whole-exome sequencing across clinical indications. Genet Med 18:696–704. CrossRefGoogle Scholar
  36. Rodrigues VJ, Elsayed S, Loeys BL, Dietz HC, Yousem DM (2009) Neuroradiologic manifestations of Loeys-Dietz syndrome type 1. AJNR Am J Neuroradiol 30:1614–1619. CrossRefPubMedGoogle Scholar
  37. Schepers D, Tortora G, Morisaki H, MacCarrick G, Lindsay M, Liang D, Mehta SG, Hague J, Verhagen J, van de Laar I, Wessels M, Detisch Y, van Haelst M, Baas A, Lichtenbelt K, Braun K, van der Linde D, Roos-Hesselink J, McGillivray G, Meester J, Maystadt I, Coucke P, El-Khoury E, Parkash S, Diness B, Risom L, Scurr I, Hilhorst-Hofstee Y, Morisaki T, Richer J, Desir J, Kempers M, Rideout AL, Horne G, Bennett C, Rahikkala E, Vandeweyer G, Alaerts M, Verstraeten A, Dietz H, Van Laer L, Loeys B (2018) A mutation update on the LDS-associated genes TGFB2/3 and SMAD2/3. Hum Mutat 39:621–634. CrossRefPubMedPubMedCentralGoogle Scholar
  38. Sharma RK (2013) Craniosynostosis. Indian J Plast Surg 46:18–27. CrossRefPubMedPubMedCentralGoogle Scholar
  39. Tan HL, Glen E, Topf A, Hall D, O’Sullivan JJ, Sneddon L, Wren C, Avery P, Lewis RJ, ten Dijke P, Arthur HM, Goodship JA, Keavney BD (2012) Nonsynonymous variants in the SMAD6 gene predispose to congenital cardiovascular malformation. Hum Mutat 33:720–727. CrossRefPubMedPubMedCentralGoogle Scholar
  40. Timberlake AT, Choi J, Zaidi S, Lu Q, Nelson-Williams C, Brooks ED, Bilguvar K, Tikhonova I, Mane S, Yang JF, Sawh-Martinez R, Persing S, Zellner EG, Loring E, Chuang C, Galm A, Hashim PW, Steinbacher DM, DiLuna ML, Duncan CC, Pelphrey KA, Zhao H, Persing JA, Lifton RP (2016) Two locus inheritance of non-syndromic midline craniosynostosis via rare SMAD6 and common BMP2 alleles. Elife 5:e20125. CrossRefPubMedPubMedCentralGoogle Scholar
  41. Timberlake AT, Furey CG, Choi J, Nelson-Williams C, Loring E, Galm A, Kahle KT, Steinbacher DM, Larysz D, Persing JA, Lifton RP, Yale Center for Genome A (2017) De novo mutations in inhibitors of Wnt, BMP, and Ras/ERK signaling pathways in non-syndromic midline craniosynostosis. Proc Natl Acad Sci USA 114:E7341–E7347. CrossRefPubMedGoogle Scholar
  42. Timberlake AT, Wu R, Nelson-Williams C, Furey CG, Hildebrand KI, Elton SW, Wood JS, Persing JA, Lifton RP (2018) Co-occurrence of frameshift mutations in SMAD6 and TCF12 in a child with complex craniosynostosis. Hum Genome Var 5:14. CrossRefPubMedPubMedCentralGoogle Scholar
  43. Twigg SR, Wilkie AO (2015) A genetic-pathophysiological framework for craniosynostosis. Am J Hum Genet 97:359–377. CrossRefPubMedPubMedCentralGoogle Scholar
  44. Tzemos N, Therrien J, Yip J, Thanassoulis G, Tremblay S, Jamorski MT, Webb GD, Siu SC (2008) Outcomes in adults with bicuspid aortic valves. JAMA 300:1317–1325. CrossRefGoogle Scholar
  45. Vallely MP, Semsarian C, Bannon PG (2008) Management of the ascending aorta in patients with bicuspid aortic valve disease. Heart Lung Circ 17:357–363. CrossRefPubMedGoogle Scholar
  46. Wu M, Chen G, Li YP (2016) TGF-beta and BMP signaling in osteoblast, skeletal development, and bone formation, homeostasis and disease. Bone Res 4:16009. CrossRefPubMedPubMedCentralGoogle Scholar
  47. Wylie LA, Mouillesseaux KP, Chong DC, Bautch VL (2018) Developmental SMAD6 loss leads to blood vessel hemorrhage and disrupted endothelial cell junctions. Dev Biol 442:199–209. CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Institute of Human GeneticsUniversity Medical Center Hamburg-EppendorfHamburgGermany
  2. 2.Department of PediatricsUniversity Medical Center Hamburg-EppendorfHamburgGermany
  3. 3.GeneDxGaithersburgUSA
  4. 4.Division of Pediatric Cardiology, Department of PediatricsWashington University School of Medicine/St. Louis Children’s HospitalSt. LouisUSA
  5. 5.Division of Genetics and Genomic Medicine, Department of PediatricsWashington University School of Medicine/St. Louis Children’s HospitalSt. LouisUSA

Personalised recommendations