KATNAL2 encodes a microtubule-severing ATPase belonging to the katanin family that catalyzes ATP-dependent microtubule severing to promote rapid reorganization of cellular microtubule arrays 1. The protein localizes to basal bodies, ciliary axonemes, centrioles, and mitotic spindles, where it functions in ciliogenesis, spindle assembly, and cytokinesis 2. During spermatogenesis, KATNAL2 works in partnership with delta tubulin and KATNB1 to regulate manchette remodeling and sperm head morphology 3. Disease relevance is substantial. Biallelic KATNAL2 mutations cause male infertility through oligo-astheno-teratozoospermia, characterized by defective sperm maturation, head morphology abnormalities, and flagellar structural defects 4. Heterozygous KATNAL2 variants associate with congenital hydrocephalus and autism spectrum disorder through disruption of primary cilia and ependymal planar cell polarity in fetal radial glia, impairing cerebrospinal fluid flow and neuronal connectivity 1. Mutations also cause amorphous sperm head morphology 5. Genome-wide association studies link KATNAL2 variants to conscientiousness personality traits 6, and altered KATNAL2 expression correlates with major depressive disorder-associated brain connectivity changes 7. Clinically, KATNAL2 mutations warrant genetic screening in male infertility and neurodevelopmental disorder patients, as they represent treatable genetic etiologies despite current symptomatic management limitations.