ACTRT1 (actin-related protein T1) is an X-linked gene encoding a cytoskeletal protein with dual roles in spermatogenesis and transcriptional regulation. Functionally, ACTRT1 negatively regulates Hedgehog signaling by binding to the GLI1 promoter and inhibiting its expression 1. At the cellular level, ACTRT1 localizes to the subacrosomal region of spermatids, where it forms a multimeric complex with ACTRT2, ACTL7A, and ACTL9 proteins that anchors developing acrosomes to the sperm nucleus 2. This interaction is mediated through connections with inner acrosomal membrane protein SPACA1 and nuclear envelope proteins PARP11 and SPATA46 2. Clinically, ACTRT1 deficiency causes severe male infertility. ACTRT1 deletions result in acrosomal detachment from sperm nuclei, sperm head deformations, and fertilization failure in affected males 3. Whole exome sequencing studies confirm ACTRT1 variants as established causative genes in primary male infertility cohorts 45. Additionally, ACTRT1 functions as a tumor suppressor; loss-of-function mutations or mutations in its regulatory enhancer RNAs lead to aberrant Hedgehog pathway activation and basal cell carcinoma development 1. These findings establish ACTRT1 as a critical gene maintaining both reproductive function and cancer suppression.