VNN1 and hemoglobin measurement: The most upregulated metabolism-associated genes were RBP2, DPEP1, and PCYT1B, and the most downregulated genes were NNMT, VNN1, and CYP2C18. Out of these six genes, DPEP1, responsible for hydrolysis of several dipeptides, and nicotinamide N-methyltransferase NNMT have been demonstrated to play a role in HB pathogenesis in previous studies (Cui et al., 2019; Rivas et al., 2020).