PCR-DNA sequencing of SELL (809-bp), ABCG2 (756-bp), SLC11A1 (450-bp), FEZL (813-bp), SOD1 (334-bp), CAT (268-bp), GPX1 (534-bp), and AhpC/TSA (480-bp) revealed nucleotide sequence variations in the form of SNPs associated with mastitis tolerance/susceptibility in investigated Holstein and Brown Swiss dairy cows. Here, CAT is linked to mastitis.