MERTK is a receptor tyrosine kinase belonging to the TAM receptor family (Tyro-3, Axl, Mer), whose ligands include the vitamin K-dependent proteins growth arrest-specific protein 6 (gas6) and protein S [12], as well as the retinal dystrophy-gene products Tulp1 and Tubby [13]. Here, PROS1 is linked to Retinal dystrophy.