ENOSF1 and Hand-foot syndrome: Four studies included in this review reported the association of several SNPs in these genes (ENOSF1 rs261091 and rs2741171, TYMS/ENOSF1 rs699517 and rs2790, and TYMS rs2853741 and rs3786362) with the risk of toxicity during capecitabine treatment, especially HFS [21,22,25,32].