Developmental expression of the SH3BGR gene, mapping to the Down syndrome heart critical region

The SH3BGR gene has been recently isolated and mapped to chromosome 21 with in the Down syndrome (DS) congenital heart disease (CHD) minimal region. As a first step to evaluate the possible involvement of SH3BGR in CHD that af fect 40% of DS patients, we have analyzed by in situ hybridization the expr ession pattern of the mouse homolog gene (Sh3bgr), during development. Our results show that Sh3bgr is already expressed at embryonic day 7.75 (E7.75) in the precardiogenic mesoderm and that from E8.5 to E10.5 its expression is restricted to the heart. In subsequent developmental stages, Sh3bgr tran scripts are also detected in skeletal muscle and in some visceral smooth mu scles including urinary bladder and gut wall, but not in vascular smooth mu scle. Our results, demonstrating that Sh3bgr is expressed in earliest stage s of mouse heart development, support a possible role of this gene in heart morphogenesis and, consequently, in the pathogenesis of CHD in DS. (C) 200 0 Elsevier Science Ireland Ltd. All rights reserved.