This observation also has important genetic implications, suggesting that some breeds may be like the rare human Li-Fraumeni families where a germ line mutation in a tumour suppressor gene (TP53) results in a hereditary predisposition to several types of cancer [44] or they may resemble the situation in families with mutations in BRCA1 where the risk of developing breast and ovarian cancer is greater in relatives of affected people, rather than the cancer being transmitted as an autosomal dominant condition [45, 46]. Here, BRCA1 is linked to cancer.