The expression levels of the genes for APP (Alzheimer’s disease marker), DYRK1A, DSCR1 (Down-syndrome critical region 1), ETS2 and SOD1, all of which are located in chromosome 21, decreased to two-thirds in D21-iPSC#2, compared to T21-iPSC#12, implying that the revertant cells regained the gene expression levels of intact iPSCs. The gene discussed is APP; the disease is early-onset autosomal dominant Alzheimer disease.