Expression levels of classical MHC genes differed between MHC classes, tissues (Ellison et al. 2020; Savage et al. 2020), and pathogens (Ke et al. 2018; McDonald et al. 2020), and they covaried with environmental conditions (Ellison et al. 2020) and the time elapsed since infection (Zhu et al. 2014). Here, HLA-C is linked to infection.