A mutated Hsap\CC2D1A coding sequence that contains a pathogenic variant associated with a form of non-syndromic mental retardation in humans (a frameshift after the third DM14 domain), is expressed under the control of l(2)gd1 regulatory sequences (548bp from upstream of the translational start site and 553bp from downstream of the translational stop site are present). The frameshift results in the expressed protein containing the first 408 residues of Hsap\CC2D1A (this includes 3 of the four DM14 domains) fused to a 30 residue C-terminal nonsense peptide. The coding sequence is tagged at the N-terminal end with Tag:HA.