Version 2.78

Description

This testing provides genotypes for CYP3A4 and CYP3A5 and determines the estimated metabolic activity. CYP3A4 and CYP3A5 cytochrome P450 enzymes are involved in the hepatic metabolism of up to 50% of all clinically used drugs. There is wide variation in enzyme activity, particularly for CYP3A4 (10-100 fold), due to both genetic and non-genetic factors. The cause of much of the variation is not yet understood. The CYP3A4 and CYP3A5 enzymes have a high degree of similarity (85% amino acid sequence homology) and they metabolism largely the same set of drugs, Though many use the CYP3A4 pathway predominantly. Genotype and metabolic activity for CYP3A4 and CYP3A5 should therefore be considered together when assessing possible effects on drug response. CYP3A4 *22 decreases enzyme activity, and is present in ~8% of Caucasians. CYP3A5 *3 is a non-functional allele, so CYPA5 *3/*3 homozygotes are non-expressors of CYP3A5. CYP3A5 *3 is the predominant CYP3A5 allele in Caucasians (prevalence of ~92%) and therefore most Caucasians have reduced or absent CYP3A5 metabolism. CYP3A5 *6 and *7 lead to decreased enzyme activity. CYP3A5 *6 and *7 are present in 11-12% of Asians and African Americans, but are essentially absent in Caucasians (frequency of 0.1%). CYP3A4 *22 is typically associated with increased response to statins (lovastatin, simvastatin, and atorvastatin), with lower doses required to gain optimal response. For CYP3A5, poor metabolizers are typically expected to require standard dosing of tacrolimus. Intermediate or extensive metabolizers are expected to require a higher starting dose of tacrolimus. Fentanyl is a key pain medication that is metabolized by CYP3A4/3A5. The CYP3A5 *3 variant has decreased clearance of this active drug. Patients with the CYP3A5 *3/*3 genotype have a higher risk of adverse events than patients with one or two *1 alleles. However, CYP3A genotype and clinical variables (delivery rate, gender, co-medications, kidney disease, BMI and serum albumin) account for less than 50% of the wide variability in serum fentanyl concentration between patients with transdermal fentanyl treatment. Source: LOINC partner 1

Basic Part Properties

Part Display Name
CYP3A4 and CYP3A5 gene
Part Type
Component (Describes the core component or analyte measured)
Created On
2016-02-24
Construct for LOINC Short Name
CYP3A4 + CYP3A5 gene

LOINC Terminology Service (API) using HL7® FHIR® Get Info

CodeSystem lookup
https://fhir.loinc.org/CodeSystem/$lookup?system=http://loinc.org&code=LP207795-8

Language Variants Get Info

Tag Language Translation
zh-CN Chinese (China) CYP3A4 与 CYP3A5 基因
Synonyms: 细胞色素 P450, 家族 3, 亚家族 A, 多肽 4;cytochrome P450, family 3, subfamily A, polypeptide 4;细胞色素 P450, 家族 3, 亚家族 A, 多肽 5;cytochrome P450, family 3, subfamily A, polypeptide 5
es-ES Spanish (Spain) Gen CYP3A4 y CYP3A5
it-IT Italian (Italy) CYP3A4 & CYP3A5, gene
Synonyms: Gene CYP3A4 e CYP3A5
nl-NL Dutch (Netherlands) CYP3A4 & CYP3A5-gen
Synonyms: CYP3A4 & CYP3A5 gen