ccm2-like is required for cardiovascular development as a novel component of the Heg-CCM pathway

► Ccm2l is a novel protein with identity to Ccm2. ► ccm2l is essential for normal cardiovascular development in zebrafish. ► ccm2l is an enhancer of the Heg-CCM dilated heart phenotype. ► Overexpression of ccm2 partially rescues ccm2l morphant defects. ► Ccm2l binds Ccm1 in an interaction that requires Ccm1's NPXY/F motifs.