The occurrence of such an LOH event in the FH gene, which is frequently observed in HLRCC-associated RCC11, would be of substantial importance, thereby confirming that Knudson’s two-hit theory for tumor suppressor genes can be applied to FH. Of note, the minor existence of the wild-type allele in the tumor (Fig. 2e) was thought to be attributable to tumor heterogeneity or contamination of normal cells, including capillary endothelial cells within the dissected tumor sample. The gene discussed is FH; the disease is hereditary leiomyomatosis and renal cell cancer.