AFF2 and Parkinson disease: Indeed, CRISPR/Cas9 has been used in human induced pluripotent stem cells (hiPSCs, see below) to introduce: (i) early-onset AD-causing mutations in amyloid precursor protein (APPSwe) and presenilin 1 (PSEN1M146V) [151]; (ii) leucine-rich repeat kinase 2 (LRRK2) G2019S mutation [152], the most prevalent genetic cause of familial and sporadic PD; (iii) mutations in 10 ASD-relevant genes (AFF2/FMR2, ANOS1, ASTN2, ATRX, CACNA1C, CHD8, DLGAP2, KCNQ2, SCN2A, and TENM1) [153]; and iv) combinatorial perturbation of four SZ-associated risk genes [154].