TAF1 and Parkinsonism: XDP has been reported exclusively in patients of Filipino origin who manifest with adult-onset dystonia–parkinsonism and who all carry the founder ~ 2.6 kb SVA (short interspersed nuclear element, variable number of tandem repeats, and Alu composite) retrotransposon insertion in the TAF1 gene (Makino et al. 2007; Domingo et al. 2015; Rakovic et al. 2018; Aneichyk et al. 2018).