Table 2.

Pharmacogenes and Variants in Pediatric Cardiac Transplantation

Gene Name(s)	Protein Names	Cellular Functions	Pharmaco-variants	Alternate Variant Name(s)	Associations	MAF in EA*	MAF in AA†
ABCB1 MDR1 P-gp	ATP-binding cassette, sub-family B, member 1	Membrane efflux pump and drug transporter	rs1045642	C3435T Ile1145Ile	CC homozygotes on tacrolimus with increased steroid dependency, lower tacrolimus concentration10–12	0.571	0.205
			rs2032582	G2677C/T Ser893Ala/T hr	GG homozygotes with lower tacrolimus concentration11	0.469	0.105
ABCC2 DJS MRP2 cMRP	ATP-binding cassette, sub-family C, member 2	Membrane efflux pump and drug transporter	rs717620	−24C>T	CC homozygotes on MMF/MPA with lower discontinuation, less GI intolerance13	0.181	0.035
CYP3A4	Cytochrome P450, family 3, subfamily A, polypeptide 4	Steroid hormone and drug metabolism	rs35599367	CYP3A4*22	*22 carriers with lower tacrolimus doses to reach target concentration14	NR	NR
CYP3A5	Cytochrome P450, family 3, subfamily A, polypeptide 5	Steroid hormone and drug metabolism	rs776746	CYP3A5*3	*3 homozygotes with higher tacrolimus concentration, lower tacrolimus dose requirement, higher tacrolimus dose- adjusted concentration11,15	0.036	0.64
IMPDH1	Inosine 5′-monophosphate dehydrogenase 1	Guanine nucleotide synthesis	rs2278294	250-106G>A	GG homozygotes on MMF/MPA with reduced dose-holding or discontinuation, less GI intolerance13	0.323	0.377
			rs2228075	1245G>A/C Ala492Ala	GG homozygotes on MMF/MPA with less GI intolerance13	0.248	0.202
IMPDH2	Inosine 5′-monophosphate dehydrogenase 2	Guanine nucleotide synthesis	rs11706052	819+10T>C	C carriers on MMF/MPA with possible increased bone marrow toxicity13	0.115	0.018

^*Based on HapMap CEU Population

^†Based on HapMap ASW Population

NR – Not reported in HapMap Data; MAF – Minor Allele Frequency; EA – European-Americans; AA – African-American; MMF – mycophenolate mofetil; MPA – mycophenolic acid