These findings include the fact that administration of potent oestrogens has been shown to induce renal cancers in the Syrian hamster (Kirkman, 1959; Reznik-Schuller, 1979; Li and Li, 1990; Cavalieri et al, 2001), the presence of oestrogen and progesterone receptors in normal and malignant renal cells (Concolino et al, 1976; Ronchi et al, 1984), and the observed association with obesity, which provides a major source of oestrogen in postmenopausal women. The gene discussed is PGR; the disease is obesity due to melanocortin 4 receptor deficiency.