GSTM1 and anemia (phenotype): In terms of the feature engineering method based on palpebral conjunctival images, Shaun et al. (22) extracted R and G channel color features of eyelid conjunctiva and calculated erythema index (EI) to predict anemia, with accuracy of 70 and 72%, higher than the evaluation of three clinicians (60/57/64%), revealing strong correlations between EI and Hb.