TAF1 and X-linked dystonia-parkinsonism: CRISPR/Cas9 has also been used to treat the neurodegenerative disease X-linked dystonia-parkinsonism (XDP) by excising the SINE-VNTR-Alu (SVA) retrotransposition in intron 32 of the TAF1 gene in multiple pluripotent stem cell-derived neuronal lineages.