ABCB1 and lymphopenia: Some reports link the toxicity of everolimus to several SNPs in PI3K/AKT/mTOR pathway genes, as well as to ABCB1 (rs1045642), associated with the development of mucositis, ABCB1 (rs2032582), associated with lymphopenia, PIK3R1 (rs10515074), associated with hyperglycemia and leucopenia, and RAPTOR (rs9906827), associated with pneumonitis [45,46].