VCX3B (variable charge X-linked 3B) is an X-linked gene with poorly characterized function. Current evidence suggests potential involvement in spermatogenesis and testicular fibrosis rather than primary cognitive development. VCX3B was identified as a differentially expressed X-linked gene in Klinefelter syndrome (47,XXY) testicular tissue, where it was upregulated in fibrotic compared to non-fibrotic samples, alongside genes involved in extracellular matrix remodeling and TGF-β pathway activation 1. The gene is also located within a large deletion region (4.8 Mb) that includes multiple X-linked genes (ANOS1, VCX2, PNPLA4, VCX, STS, HDHD1, VCX3A, NLGN4X) associated with Kallmann syndrome and ichthyosis 2. Analysis of VCX3B alongside related VCX family members in X-linked ichthyosis patients with normal intelligence suggests the gene does not independently cause intellectual disability 3. While GO annotations indicate nuclear localization and potential brain development involvement, clinical evidence supporting cognitive impairment from VCX3B alone is lacking. The gene's specific role in testicular fibrosis pathogenesis requires further investigation.