RESEARCH ARTICLE The Diagnostic Value of Next Generation Sequencing in Familial Nonsyndromic Congenital Heart Defects Yaojuan Jia, 1 Jacoba J. Louw, 1,2 Jeroen Breckpot, 1,3 Bert Callewaert, 4 Catherine Barrea, 5 Yves Sznajer, 6 Marc Gewillig, 2 Erika Souche, 1 Luc Dehaspe, 1 Joris Robert Vermeesch, 1 Diether Lambrechts, 7,8 Koenraad Devriendt, 1 and Anniek Corveleyn 1 * 1 Department of Human Genetics, KU Leuven, Leuven, Belgium 2 Department of Congenital and Pediatric Cardiology, University Hospitals Leuven, Leuven, Belgium 3 Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium 4 Center for Medical Genetics, University of Ghent, Ghent, Belgium 5 Department of Congenital and Pediatric Cardiology, Universit,  e, Catholique de Louvain, Brussels, Belgium 6 Center for Human Genetics, Universit e Catholique de Louvain, Brussels, Belgium 7 Department of Oncology, KU Leuven, Leuven, Belgium 8 Vesalius Research Center, VIB, Leuven, Belgium Manuscript Received: 9 October 2014; Manuscript Accepted: 19 March 2015 To determine the diagnostic value of massive parallel sequencing of a panel of known cardiac genes in familial nonsyndromic congenital heart defects (CHD), targeted sequencing of the coding regions of 57 genes previously implicated in CHD was performed in 36 patients from 13 nonsyndromic CHD families with probable autosomal dominant inheritance. Following vari- ant analysis and Sanger validation, we identified six potential disease causing variants in three genes (MYH6, NOTCH1, and TBX5), which may explain the defects in six families. Several problematic situations were encountered when performing ge- notype-phenotype correlations in the families to confirm the causality of these variants. In conclusion, by screening known CHD-associated genes in well-selected nonsyndromic CHD families and cautious variant interpretation, potential causative variants were identified in less than half of the families (6 out of 13; 46%). Variant interpretation remains a major challenge reflecting the complex genetic cause of CHD. 2015 Wiley Periodicals, Inc. Key words: congenital heart defects; genetic testing; massive parallel sequencing INTRODUCTION Isolated CHD are generally thought to have a multifactorial origin, though in a small proportion of cases, estimated at 4%, there is a clear familial recurrence [Oyen et al., 2009; Oyen et al., 2010; van der Bom et al., 2011], suggesting a single genetic cause. The inheritance pattern is typically autosomal dominant with variable expression and reduced penetrance. More rarely, autosomal reces- sive or X-linked inheritance exists. Traditional cloning approaches have led to the identification of a large number of genes for nonsyndromic CHD [Schott et al., 1998; Garg et al., 2003; Garg et al., 2005; Kirk et al., 2007], but each of these genes is implicated only in a small proportion of familial CHD. Genes associated with CHD can be found in CHDWiki [Barriot et al., 2010] (http://www. esat.kuleuven.be/~bioiuser/chdwiki). Traditional genetic diagnosis of a large panel of candidate genes suffers from limitations in sequencing capacity. Nowa- How to Cite this Article: Jia Y,Louw JJ, Breckpot J, Callewaert B, Barrea C, Sznajer Y, Gewillig M, Souche E, Dehaspe L, Vermeesch JR, Lambrechts D, Devriendt K, Corveleyn A. 2015. The diagnostic value of next generation sequencing in familial nonsyndromic congenital heart defects. Am J Med Genet Part A 9999A:1–8. Conflict of interest: None.  Correspondence to: Anniek Corveleyn, Department of Human Genetics, KU Leuven, Herestraat 49, B3000 Leuven, Belgium. E-mail: anniek.corveleyn@uzleuven.be Article first published online in Wiley Online Library (wileyonlinelibrary.com): 00 Month 2015 DOI 10.1002/ajmg.a.37108 Ó 2015 Wiley Periodicals, Inc. 1