Pintip NgamjanyapornAmmarin ThakkinstianOravan VerasertniyomPorntip ChatchaipunMonchand VanichapuntuKanokrat NantirujKitti TotemchokchyakarnJohn AttiaSuchela JanwityanujitMahidol UniversityUniversity of Newcastle, Australia2018-05-032018-05-032011-09-01Rheumatology International. Vol.31, No.9 (2011), 1215-12181437160X017281722-s2.0-80054945119https://repository.li.mahidol.ac.th/handle/123456789/12001To assess whether the CYP2C19 polymorphism modified the effect of cyclophosphamide on ovarian toxicity in Thai patients with SLE. We performed a case-control study of female patients with SLE who were treated with cyclophosphamide at Ramathibodi Hospital, Bangkok, Thailand. Cases were patient who had ovarian toxicity (sustained amenorrhoea > 12 months or lack of menstruation for > 4 months). CYP2C19 polymorphism was genotyped using PCR-RFLP method. Logistic regression was applied to assess CYP2C19 polymorphism as an effect modifier of cyclophosphamide. Seventy-one patients with SLE were enrolled, of which 36 (59.7%) had ovarian toxicity. CYP2C19*2 allele frequencies were 27.8 and 21.4% in the ovarian and non-ovarian toxicity groups. Patients with CYP2C19*1/*1 genotype and higher cumulative dose of cyclophosphamide ( > 23.75 g) had the highest odds of ovarian toxicity, i.e. 11.0 (95% CI: 1.2-99.1) times higher than patients with the CYP2C19*1/ *2 or*2/*2 genotypes who received less cyclophosphamide ( < 23.75 g). After adjusting for age at start of treatment, this risk increased to 13.6 (95% CI: 1.1-162.2). Our results suggest that a cumulative cyclophosphamide dose of 23.75 g or higher carries a twofold higher risk of ovarian toxicity and the CYP2C19*1/*1 genotype increases the risk of toxicity a further fivefold. © 2010 Springer-Verlag.Mahidol UniversityImmunology and MicrobiologyMedicineArticleSCOPUS10.1007/s00296-010-1420-7