TAF7L (TATA-box binding protein associated factor 7 like) is an X-linked gene that encodes a spermatogenesis-specific component of the TFIID transcription factor complex, playing a crucial role in male fertility. The protein functions in RNA polymerase II transcription initiation and preinitiation complex assembly, serving as a germ cell-specific paralogue of the generally expressed TAF7 1. TAF7L is essential for normal spermatogenesis and sperm function, as demonstrated by mouse studies showing that Taf7l deficiency results in reduced testis weight, decreased sperm count, abnormal sperm morphology including folded tails, and impaired sperm motility 1. The gene regulates transcription of spermatogenesis-related genes, including FSCN1, an F-actin-bundling protein critical for sperm structure 1. Clinically, deleterious variants in TAF7L cause oligoasthenoteratozoospermia (OAT) in humans, with mutations leading to impaired histone-to-protamine exchange affecting sperm chrX compaction 2. Multiple pathogenic variants have been identified in OAT patients, including frameshift and missense mutations that result in reduced protein expression or truncated proteins 2 3. TAF7L mutations represent a significant genetic cause of male infertility, accounting for approximately 8% of isolated non-obstructive azoospermia cases 4.