Genetic Determinants of Clozapine-Induced Metabolic Side Effects.
Atypical antipychotics are linked to a higher incidence of metabolic side effects, including weight gain, dyslipidemia, and diabetes. In this study, we examined the prevalence and potential genetic predictors of metabolic side effects in 60 adult patients on clozapine.



Genetic variants of relevance to clozapine metabolism, clearance, and response were assessed through targeted genotyping of cytochrome P450 enzymes CYP1A2 and CYP2C19, the efflux transporter ABCB1, the serotonin receptor (HTR2C), leptin (LEP), and leptin receptor (LEPR). Clozapine levels and other potential confounders, including concurrent medications, were also included in the analysis.



More than half of the patients were obese (51%), had metabolic syndrome (52.5%), and 30.5% were overweight. There was a high prevalence of antipsychotic polypharmacy (61.9%). With multivariable linear regression analysis, LEP -2548G>A, LEPR c.668A>G, and HTR2C c.551-3008 C>G were identified as genetic predictors of body mass index (BMI) after considering effects of clozapine dose, blood level, and concurrent medications (adjusted R2= 0.305). Metabolic syndrome was found to be significantly associated with clozapine level and CYP2C19*2 and LEPR c.668 G alleles. Clozapine levels in patients with metabolic syndrome were significantly higher compared to those without metabolic syndrome (1886 ± 895 vs. 1283 ± 985 ng/mL, P < 0.01) and were associated with the CYP2C19*2 genotype. No association was found between the genetic variants studied and lipid or glucose levels.



This study confirms a high prevalence of metabolic side effects with clozapine and suggests higher clozapine level and pharmacogenetic markers in CYP2C19, LEP, LEPR, and HTR2C receptors as important predictors of BMI and metabolic syndrome.
1 Departments of Psychiatry and Medicine, Western University, London, Ontario.
Kamini
K
Vasudev
2 Department of Epidemiology and Biostatistics, Western University, London, Ontario.
Yun-Hee
YH
Choi
3 Department of Psychiatry and Epidemiology and Biostatistics, Western University, London, Ontario.
Ross
R
Norman
4 Department of Medicine, Physiology & Pharmacology, and Oncology, Western University, London, Ontario.
Richard B
RB
Kim
4 Department of Medicine, Physiology & Pharmacology, and Oncology, Western University, London, Ontario.
Ute I
UI
Schwarz
D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000009:adverse effects*; D003024:Clozapine / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000139:chemically induced / Q000235:genetics; D050177:Overweight / Q000139:chemically induced* / Q000235:genetics; D000071185:Pharmacogenomic Testing; D015995:Prevalence; D011618:Psychotic Disorders / Q000188:drug therapy*; D012559:Schizophrenia / Q000188:drug therapy*; D055815:Young Adult
D014150:Antipsychotic Agents; D003577:Cytochrome P-450 Enzyme System; D003024:Clozapine
clozapine; metabolism; pharmacogenetics; pharmacokinetics
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