GPX1 and Cowden disease: Interestingly, one SNP in GPX1 (rs1800668), one SNP in GPX3 (rs3792797), three SNPs in DIO1 (rs12095080, rs2294511 and rs2294512), two SNPs in DIO2 (rs225011 and rs225012), two SNPs in SEPHS1 (rs17529609 and rs7901303), three SNPs in SEPSECS (rs11937742, rs1553153 and rs2302565) and one SNP in TXNRD2 (rs1548357) (Table 5) were significantly associated with modified selenium levels indicating that these genes might increase the risk of developing CD.