As to CD45 on CD33br HLA DR+, positive associations with a higher risk of mastitis were also observed by MR Egger (OR = 1.086, 95% CI = 1.014~ 1.163, p = 0.034), Weighted median (OR = 1.099, 95% CI = 1.016~ 1.188, p = 0.018) and Weighted mode methods (OR = 1.100, 95% CI = 1.027~ 1.179, p = 0.016). This evidence concerns the gene PTPRC and mastitis.