A role of the human PAOD1 gene, a. k. a. prostaglandin E receptor subtype EP3 or PTGER3, in peripheral arterial occlusive disease is disclosed, as are nucleic acids encoding several subtypes of the receptor comprising novel exons 4 and 5. Methods for diagnosis, prediction of clinical course and treatment for peripheral occlusive disease using polymorphisms in the PAOD1 gene are also disclosed.