IRS1 and dementia: Not only the APP gene is responsible for dementia in DS, GATD3A, SOD1, ERG, BACE2, DSCR1/RCAN1, APOE (19q13.32), BACE1 (11q23.3), IL1B (2q14.1), GSAP (7q11.23), UBB (17p11.2), and IRS1 (2q36.3) genes may also play a major role in dementia in DS.