Cyp2C19 Genotype Does Not Represent A Genetic Predisposition In Idiopathic Systemic Lupus Erythematosus

Background-The aetiology of systemic lupus erythematosus (SLE) is still unknown. In several cases, however, chemicals or drugs were identified as aetiological agents and associations with certain phenotypes of drug metabolising enzymes have been reported. The purpose of this study was to discover if there is an association between CYP2C19 polymorphism and susceptibility to SLE. Methods-Racemic mephenytoin (100 mg orally) was given to healthy volunteers (n=161) and SLE patients (n=37) and then S-mephenytoin and R-mephenytoin were determined in eight hour urine samples. A 10 ml blood sample was obtained from healthy volunteers (n=80) and SLE patients (n=69) for genotypic assay. Each blood sample was tested for the detection of CYP2C19*1 and CYP2C19*2 (formerly wt and mi respectively) by oligonucleotide ligation assay. Results-The ratio of SIR-mephenytoin ranged from <0.1 to 1.293 in healthy subjects and from <0.1 to 1.067 in SLE patients. FM phenotype was observed in 2 of 37 patients with idiopathic SLE (5.4 %) and 6 of 161 healthy subjects (3.7 %). There were no significant differences in the frequency of PM phenotypes between the groups (Fisher's exact test, p= 0.64) or in the frequency distribution profiles of ratios of S-mephenytoin to R-mephenytoin. No significant differences in distribution of overall genotypes and in allele frequencies were observed between the two groups. No significant relation was found between clinical features and the overall genotype. Conclusion-The results of this study indicate that CYP2C19 genotype does not represent a genetic predisposition in idiopathic SLE patients.WoSScopu

The effect of polymorphic metabolism enzymes on serum phenytoin level

Phenytoin has a widespread use in epilepsy treatment and is mainly metabolized by hepatic cytochrome P450 enzymes (CYP). We have investigated CYP2C9*2, CYP2C9*3, CYP2C19*2 and CYP2C19*3 allelic variants in a Turkish population of patients on phenytoin therapy. Patients on phenytoin therapy (n = 102) for the prevention of epileptic seizures were included. Polymorphic alleles were analyzed by restriction fragment length polymorphism method. Serum concentrations of phenytoin were measured by fluorescence polarization immune assay method. The most frequent genotype was detected for CYP2C9 wild-type alleles (78.43 %), whereas CYP2C19*2/*2 (5.88 %) was the least frequent genotype group. According to the classification made with both enzyme polymorphisms, CYP2C9*1/*1-CYP2C19*1/*1 (G1: 41.17 %) genotype group was the most frequent whereas CYP2C9*1/*2-CYP2C19*1/*3 (G7: 0.98 %) was the least frequent one. The highest mean phenytoin level (27.95 +/- A 1.85 A mu g/ml) was detected in the G8 genotype group (CYP2C9*1/*3-CYP2C19*2/*3) and the G1 genotype group showed the lowest mean phenytoin level (7.43 +/- A 0.73 A mu g/ml). The mean serum concentration of phenytoin of the polymorphic patients with epilepsy was higher than that for the wild-type alleles both in the monotherapy and polytherapy patients. These results show the importance of the genetic polymorphism analysis of the main metabolizing enzyme groups of phenytoin for the dose adjustment