Michele Carbone and colleagues, from the University of Hawaii, discovered that members of 4 families, apparently unrelated and living in different US States, shared the identical mutation of a gene called BAP1 that is associated with a higher incidence of mesothelioma, melanoma, renal carcinoma and other cancers.
This raised two possibilities:
1) These 4 families were related although they did not know it, or
2) The researchers had found a hot spot for BAP1 mutations.