ABCB1 and ABCC1 single-nucleotide polymorphisms in patients treated with clozapine.

Clozapine (CZ) has superior efficacy to other antipsychotic agents in the treatment of schizophrenia and has been extensively used in clinical practice. ATP-binding cassette (ABC) transporter proteins are responsible for the distribution of various molecules as well as drugs across extracellular and intracellular membranes, including the blood-brain barrier. Genetic variations in these proteins can account for differences in treatment response. We investigated the influence of rs1045642 and rs212090 single-nucleotide polymorphisms (SNPs) on CZ serum level, clinical outcome, and changes in body mass index (BMI) in the first year of CZ treatment. These polymorphisms influenced baseline BMI in males (=0.009 and 0.054, B1 and C1, respectively), changes in BMI in males after 3 (=0.026, ) and 12 months (=0.022, ) of CZ treatment, and level of diastolic pressure (=0.002 and 0.051, respectively). The combination of + homozygote SNPs was associated with increased CZ and norclozapine serum levels (=0.054 and 0.010, respectively). ABC transporter SNPs could be potential biomarkers for CZ-induced weight gain and cardiovascular complications. Further pharmacogenetic research is warranted to help clinicians with their treatment decision, including concomitant use of drugs and prevention of side effects.