Abstract Congenital heart disease (CHD) is the most com- mon birth defect in humans and is present in 40% of new- borns affected by Down syndrome (DS). The SH3BGR gene maps to the DS-CHD region and is a potential can- didate for the pathogenesis of CHD, since it is selectively expressed in cardiac and skeletal muscle. To determine whether overexpression of Sh3bgr in the murine heart may cause abnormal cardiac development, we have gen- erated transgenic mice using a cardiac- and skeletal-mus- cle-specific promoter to drive the expression of a Sh3bgr transgene. We report here that heart morphogenesis is not affected by overexpression of Sh3bgr. Introduction A 5-Mb region in 21q22.2 encompassing D21S55 to MX1 has been associated with congenital heart disease (CHD) present in 40% of newborns affected by Down syndrome (DS). The complete sequencing of human chromosome 21 has recently shown that this region contains less than 30 genes (Hattori et al. 2000). The functional characterization of these genes is a crucial step towards the identification of genes involved in the pathogenesis of DS-CHD. The SH3BGR gene maps to the DS-CHD critical region and has been previously isolated by cDNA selection in an ef- fort to identify genes that are located in this region and that are expressed in the developing heart (Scartezzini et al. 1997). An expression study in the mouse has revealed that the corresponding murine gene is expressed in the heart from early stages of embryonic development (Egeo et al. 2000). The mechanisms by which an extra copy of chromo- some 21 results in the various clinical aspects of DS are still unknown. It remains to be established whether the de- fects seen in DS are attributable to the overexpression of specific individual genes or small groups of genes located on the triplicated chromosome (Chrast et al. 2000) or to a general stochastic deregulation of transcription when three copies of the chromosome are present (Saran et al. 2003). The use of both microarray approaches and single gene overexpression will be necessary to dissect the molecular mechanisms that underlie the development of DS pheno- type. We have used a transgenic approach to explore the functional role of the Sh3bgr gene in heart development and its possible involvement in DS-CHD. Materials and methods Two different constructs, one containing only the mouse Sh3bgr gene and another also containing a lacZ gene placed after an inter- nal ribosomal entry site element, were used for the production of the transgenic lines on an FVB genetic background (Fig. 1A). Gene expression in both constructs was driven by the beta/slow MyHC promoter that, in mouse embryos, is expressed exclusively in heart and skeletal muscle (Knotts et al. 1996). We obtained sev- eral transgenic lines (Fig. 1B); however, only two lines (164 and 192) were found to express the transgene (not shown). The Sh3bgr level of expression in the two transgenic lines was analyzed by real-time polymerase chain reaction (PCR). Results and discussion As shown in Fig. 1C, a moderate but significant overexpres- sion of Sh3bgr gene (1.6 for line 164 and 2.1 for line 962) was observed at day 17 of embryonic development (E17) in the hearts of transgenic embryos compared with wild- type littermates. Claudia Sandri · Raffaella Di Lisi · Anne Picard · Carla Argentini · Elisa Calabria · Kristene Myklak · Paolo Scartezzini · Stefano Schiaffino Heart morphogenesis is not affected by overexpression of the Sh3bgr gene mapping to the Down syndrome heart critical region Hum Genet (2004) 114 : 517–519 DOI 10.1007/s00439-004-1088-8 Received: 30 October 2003 / Accepted: 12 January 2004 / Published online: 7 February 2004 SHORT REPORT C.S. and R.D.L. contributed equally to this work C. Sandri · R. Di Lisi · K. Myklak · S. Schiaffino Venetian Institute of Molecular Medicine, Via Orus 2, 35129 Padua, Italy A. Picard · C. Argentini · E. Calabria · S. Schiaffino (✉) Department of Biomedical Sciences, University of Padua, Viale G. Colombo 3, 35121 Padua, Italy Tel.: +39-49-8276034, Fax: +39-49-8276040, e-mail: stefano.schiaffino@unipd.it P. Scartezzini Laboratorio Biomolecolare, Dipartimento di Gerontologia, Ospedale Galliera Mura delle Cappuccine 14, 16128 Genoa, Italy © Springer-Verlag 2004