1. The aetiology is not completely understood, but environmental factors, including female sex hormones, ultraviolet light exposure and infections, play an important part, as does a genetic predisposition with genetic polymorphisms in immunoglobulin-Fc receptor genes, cytokine genes, complement genes and genes regulating apoptosis.

Hier sind genetische Polymorphismen in Immunglobulin-Fc-Rezeptor-Genen, Komplementgenen, Zytokingenen und in Genen, die die Apoptose regulieren, zu nennen.