ABSTRACT
The hematopoietic system is critical for the viability of the human body. Erythrocytes play
the major role in tissue oxygenation, platelets keep the vasculature intact, and white cells
are a primary line of defense against infectious pathogens, among their other roles. In
addition, the hematopoietic system is an important component of many common diseases,
including cardiovascular, central nervous system (CNS), renal, and cancer. Major
advances in the treatment of hematologic disorders have resulted from the recent
revolution in medical interventions. However, significant heterogeneity in the efficacy
and toxicity of drugs is consistently observed across the human population (1). Adminis-
tration of the same dose of a given drug to a population of patients results in a range of
toxicity, from unaffected to lethal events (2,3). Although many clinical variables have
been associated with drug response (age, gender, diet, organ function, disease biology),
genetic differences in drug disposition and drug targets can have a great impact on treat-
ment outcome (1,4,5). The metabolic enzymes and cellular targets for the majority of che-
motherapeutic agents contain genetic polymorphisms (6), but prospective identification of
patients likely to benefit from (or be harmed by) chemotherapy is not currently possible for
most treatments. This is particularly important in the current health care environment,
where cost containment and evidence-based initiatives are having a significant influence
on patient care.
