To localize the genetic defect in a Turkish family with three siblings affected by COD or CRD (family A; Figure 1A), we performed exome sequencing in A-II:1. Putative causal mutations were selected when present with a frequency < 0.5% in dbSNP and our in-house controls (n = 2,604 alleles) and when they represented nonsense, frameshift, canonical splice-site, or missense mutations with a PhyloP score > 2.7 (range −14.1–6.4).25 Under the assumption of autosomal-recessive inheritance, we identified potential compound-heterozygous mutations (present in >20% sequence-variant reads) in ASTE1, CNTN3 (MIM 601325), and TUBGCP2; Sanger sequencing of these mutations showed that they did not segregate with the disease. We identified one potential homozygous mutation (present in >80% sequence-variant reads; Table S3), c.317C>G (p.Arg106Pro) in POC1B (MIM 614784), and upon Sanger sequence analysis, it was found to be present in a homozygous state in the three affected siblings and in a heterozygous state in the parents and unaffected sibling (Figure 1A). The arginine at position 106 is highly conserved up to Chlamydomonas (Figure 1C). The c.317 position has a high PhyloP score of 6.1, and the c.317C>G mutation was not identified in 189 ethnically matched controls or in the NHLBI Exome Sequencing Project Exome Variant Server (EVS, release ESP6500).