HIF1A and cyst: However, in a subsequent analysis, the same authors showed that mice carrying the double deletion of Fh1 and Hif1α genes did not suppress the development of cystic disease, at the contrary, Hif1α deficiency accelerated and exacerbated cyst formation (10), hence casting serious doubts on the role of the “pseudo-hypoxia” drive in Fh-dependent tumorigenesis.