TYMS and cancer: ENOSF1 (enolase super family 1 [MIM: 607427]) has been shown to modify TYMS expression at the RNA level by acting as an antisense molecule to TYMS. 34,35ENOSF1 partially overlaps TYMS on chromosome 18 and is transcribed in the opposite direction to TYMS. 5-FU is a common treatment in cancer-affected individuals, and many reports demonstrate a pharmacogenetic link between several SNPs in the TYMS-ENOSF1 locus36 and the development of severe hand-foot syndrome.37