CBR3 and cardiomyopathy: Of further note, the metabolic studies of CBR3 variants also showed that both wild-type and variant recombinant CBR3 protein was able to metabolize doxorubicin 1.5-fold more efficiently than daunorubicin [35], suggesting that perhaps individuals deemed at higher risk of cardiomyopathy due to CBR3 variants might have less cardiotoxicity from daunorubicin.