contribute a part of this puzzle. CNVs include insertions, deletions and duplications and encompass relatively large genomic segments of 1 kb to several Mb in size (Redon et al. 2006; Sebat et al. 2004). Although they are a frequent class of polymorphism in the human genome, most CNVs are rare. Many reports indeed now suggest involvement of CNVs in psychiatric disorders (Lachman et al. 2007; Marshall et al. 2008; Sebat et al. 2007; Stefansson et al. 2002, 2008; Szatmari et al. 2007b; Ullmann et al. 2007; Vrijenhoek et al. 2008; Walsh et al. 2008; Weiss et al. 2008). The role of CNVs in ADHD has not been studied, yet.
