Since genistein can cross the blood–brain-barrier (Tsai 2005), and it was demonstrated to be safe when used for a long time (over 1 year) at concentration as high as 150 mg/kg/day during a clinical trial (Kim et al. 2013), we aimed to test effects of this isoflavone on mutated huntingtin in HEK-293 cells expressing the HTT gene exon 1 with 74 CAG repeats which is a commonly used cellular model of HD. Here, HTT is linked to Huntington disease.