While investigating the cause of Grb2 upregulation in HD model we found several transcription factor binding sites in the upstream DNA sequence of Grb2 and, through rational selection, checked the regulation of Grb2 by Forkhead Box D3 (Foxd3), a member of the forkhead box (Fox) family of transcription factors [11]. This evidence concerns the gene FOXD3 and Huntington disease.