Defects in the proα1(V)- or the proα2(V)-chain, encoded by COL5A1 and COL5A2 respectively, lead to classic Ehlers-Danlos Syndrome (EDS), formerly known as EDS type I, “gravis” (MIM# 130000) and EDS type II, “mitis” (MIM# 130010). The gene discussed is COL5A1; the disease is Ehlers-Danlos syndrome.