Clinical diagnosis of VHL is as follows: when there is a relative affected, the presence of a single CNS Hb, pheochromocytoma or ccRCC confirms the diagnosis; while in the absence of familiar history, the presence of 2 CNS Hbs, or 1 CNS Hb and other visceral tumour, is required. This evidence concerns the gene GSTM1 and von Hippel-Lindau disease.