Genes upregulated in subfertile mares without clinical signs of uterine diseases compared to fertile mares were mainly related to ‘monocarboxylic acid transmembrane transporter activity’ (SLC10A2, SLC16A5, SLC16A9) and protein targeting (RPS17, RPL21, TOMM7, 60S ribosomal protein L26-like pseudogene, 40S ribosomal protein S2 pseudogene). The gene discussed is SLC16A9; the disease is uterine disorder.