Digital clubbing is usually secondary to different acquired diseases. Primary hypertrophic osteoarthropathy (PHO) is a rare hereditary disorder with variable digital clubbing as the most prominent feature, subperiosteal new bone formation, and arthropathy. Recently, mutations in the 15-hydroxy-prostaglandin dehydrogenase (15-PGDH) encoding gene HPGD were found to cause PHO. Here, we identified three unrelated families with different mutations in the prostaglandin transporter (PGT) encoding gene SLCO2A1 which presumably result in reduced metabolic clearance by 15-PGDH due to diminished cellular uptake of prostaglandin E2 (PGE2) by mutant PGT. In two consanguineous families, homozygous mutations, an intragenic deletion that results in frameshift and a missense mutation, are associated with a severe PHO phenotype. In a third family, a heterozygous carrier of a stop mutation presents with isolated digital clubbing. Thus, our study further supports the importance of PGE2 metabolism in the pathogenesis of digital clubbing and PHO. Hum Mutat 33:660664, 2012. (c) 2012 Wiley Periodicals, Inc.