Factors of Steroid Dependency in Idiopathic Nephrotic Syndrome

The primary purpose of the study is to identify the factors of steroid dependency in childhood idiopathic nephrotic syndrome. The steroid dependency is defined by a relapse of nephrotic syndrome within the 3 weeks that follow the withdrawal of steroid therapy after the first manifestation. Different clinical and biological factors will be analyzed: age of first manifestation, delay of remission, ethnicity, and preceding viral infection, geolocalization in the Parisian area, genoprevalence of herpes viruses and polymorphisms in the genes involved in the response to steroid therapy.