Association of ABCB1, CYP3A4, EPHX1, FAS, SCN1A, MICA, and BAG6 polymorphisms with the risk of carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in Chinese Han patients with epilepsy.

OBJECTIVE: This study explored the association between the risk of carbamazepine (CBZ)-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) and CBZ dose, dose-adjusted concentration, and ABCB1, CYP3A4, EPHX1, FAS, SCN1A, MICA, and BAG6 polymorphisms in patients of Han ethnicity with epilepsy who were living in northeastern China.

MATERIALS AND METHODS: We determined the genotypes of patients with CBZ-SJS/TEN and CBZ-tolerant patients, who were used as controls, for ABCB1, CYP3A4, EPHX1, FAS, SCN1A, MICA, and BAG6 polymorphisms by polymerase chain reaction (PCR) amplification and direct sequencing. We measured the steady-state serum CBZ concentrations using fluorescence polarization immunoassay for the control patients.

RESULTS: We observed statistically significant differences in EPHX1 c.337T>C polymorphisms between patients with CBZ-SJS/TEN and CBZ-tolerant controls in terms of allelic and genotypic frequencies (p = 0.011 and p = 0.007, respectively). The C allele and the C-G diplotype of EPHX1 may play important roles in increasing the risk of CBZ-SJS/TEN development (odds ratio [OR] 0.478, 95% confidence interval [CI] = 0.267-0.855, p = 0.011; OR = 0.213, 95% CI = 0.049-0.930, p = 0.025, respectively). We did not observe any significant associations between ABCB1, CYP3A4, EPHX1, FAS, SCN1A, MICA or BAG6 genes and CBZ dose or dose-adjusted concentration in CBZ-tolerant patients.

SIGNIFICANCE: We found a significant association between EPHX1 c.337T>C polymorphisms and the development of CBZ-SJS/TEN in patients of Han ethnicity living in northeastern China. EPHX1 c.337T>C polymorphisms may contribute to the risk of severe CBZ-SJS/TEN by increasing the concentration of a CBZ metabolite, CBZ-10,11-epoxide, in patients with epilepsy.