WBP4 (WW domain binding protein 4) is a spliceosome component that plays a critical role in pre-mRNA splicing by facilitating cross-intron bridging of U1 and U2 snRNPs in the mammalian A complex 1. The protein is essential for proper RNA processing, and complete loss of WBP4 protein leads to abnormal splicing patterns affecting genes associated with nervous system and musculoskeletal development 1. Mechanistically, WBP4 functions as part of the early spliceosomal complex and has been identified as interacting with various proteins including the vitamin D receptor, where it controls VDR subcellular localization 2. The gene has significant disease relevance as bi-allelic loss-of-function variants cause a severe neurodevelopmental syndrome characterized by hypotonia, global developmental delay, intellectual disability, brain abnormalities, and musculoskeletal defects 1. This condition represents a newly described spliceosomopathy, adding to the growing list of diseases caused by spliceosome dysfunction 1 3. Clinical significance extends to its potential role as a biomarker, as WBP4 has been identified in RNA-binding protein signatures for predicting biochemical recurrence in prostate cancer 4.