Advancements in the Study of Clinical Features and Molecular Functions in Heterogeneous TAF1-associated Clinical Phenotypes

Purpose of review: TATA-binding protein (TBP)-associated factor 1 (TAF1) encodes the largest component of the transcription factor IID (TFIID) complex, which binds to core promoters and serves as a scaffold for assembly of the RNA polymerase II transcription complex. Variants in TAF1 are associated with X-linked dystonia-parkinsonism (XDP) and X-linked syndromic mental retardation-33 (MRXS33). This review provides a concise summary of the genetic and clinicopathological features of TAF1 variants related to phenotype. Recent findings: XDP is an adult-onset X-linked progressive neurodegenerative disorder presenting dystonia and parkinsonism and caused by a SINE-VNTR-Alu (SVA)-type retrotransposon within TAF1. TAF1/MRXS33 intellectual disability syndrome is characterized by global developmental delay, intellectual disability, facial dysmorphia, generalized hypotonia, and neurological abnormalities due to the missense variants in TAF1. Various symptoms of TAF1 missense mutations may be related to mutations in different functional regions of the protein. The clinical manifestations of XDP and MRXS33, both caused by variants of TAF1, present prominent heterogeneity, which could be influenced by whether the TAF1 mutation is located in the coding region, the time when TAF1 expression decreases, and the effect on downstream gene expression. Summary: TAF1 is linked to many different phenotypes because of its variable regulation of coding and noncoding elements, which makes its mechanistic roles in disease challenging to interpret. However, it is important to note that strategies to correct TAF1 splicing could provide therapeutic benefits in different diseases.