title: Impact of ATP-binding cassette, subfamily B, member 1 pharmacogenetics on tacrolimus-associated nephrotoxicity and dosage requirements in paediatric patients with liver transplant.
abstract: BACKGROUND
  Tacrolimus is the most commonly used immunosuppressive agent following solid-organ transplantation in children. Its clinical use, however, is complicated by side effects (mainly nephrotoxicity), narrow therapeutic index and pharmacokinetic variability which can result in an increased risk of treatment failure or toxicity. Studies examining interindividual differences in the expression of the ABCB1 (ATP-binding cassette, subfamily B, member 1) gene (which encodes the drug transporter, P-gp) and its genetic polymorphisms have attempted to elucidate variations in tacrolimus response and disposition in children.
  
  
  METHODS
  This review explores pharmacogenetic knowledge developed over the last decade regarding the impact of ABCB1 polymorphisms on tacrolimus toxicity and dosage requirements in children.
  
  
  RESULTS
  A better understanding of the role of ABCB1 genetic polymorphisms (and corresponding haplotypes) and ABCB1 expression levels in various tissues and organs on tacrolimus outcomes in children with liver transplant.
  
  
  CONCLUSIONS
  Pharmacogenetics offers significant potential for optimising tacrolimus use. ABCB1 donor genotypes and ABCB1 expression level in the intestine and leukocytes may be useful in dosage selection. Large prospective studies are, however, required to further explore the potential of genetic testing in identifying children who are at risk of toxicity and to better individualise tacrolimus therapy.
authors.affiliation: Queen's University Belfast, Medical Biology Centre, School of Pharmacy, Clinical and Practice Research Group, 97 Lisburn Road, Belfast, UK.
authors.forename: Ahmed F
authors.initials: AF
authors.lastname: Hawwa
authors.forename: James C
authors.initials: JC
authors.lastname: McElnay
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics*; D000818:Animals; D002648:Child; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000009:adverse effects*; D007674:Kidney Diseases / Q000139:chemically induced* / Q000235:genetics* / Q000378:metabolism; D016031:Liver Transplantation; D010597:Pharmacogenetics / Q000379:methods; D011110:Polymorphism, Genetic; D016559:Tacrolimus / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: C513055:ABCB1 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007166:Immunosuppressive Agents; D016559:Tacrolimus