ARL2BP (ARL2 binding protein) is a ciliary effector protein that functions as a regulator of primary cilia structure and photoreceptor maintenance. ARL2BP localizes to the basal body and cilium-associated structures of photoreceptors, where it works with the small GTPase ARL2 to maintain ciliary length and stability 1. The protein plays a critical role in ciliary microtubule organization and is essential for normal spermiogenesis and sperm flagellar assembly 2. Mutations in ARL2BP cause autosomal-recessive retinitis pigmentosa (RP66), characterized by progressive photoreceptor degeneration leading to visual failure 13. ARL2BP mutations account for approximately 0.1% of autosomal recessive rod-cone dystrophies 3. Beyond retinal disease, homozygous ARL2BP variants present as syndromic ciliopathies, including situs inversus totalis, male infertility with oligozoospermia or asthenozoospermia, and olfactory dysfunction 425. Disease-causing mutations impair ARL2BP localization at the basal body, reduce ARL2 binding, and result in cilia shortening and abnormal ciliogenesis 1. Recent findings expand the syndromic phenotype to include renal agenesis with microcysts 5, necessitating differential diagnosis with Senior-Loken and Bardet-Biedl syndromes in patients presenting with retinal dystrophy and renal abnormalities.