HSF4 and cataract: Of those families with inherited cataracts for whom the mutant gene is known, about half show mutations in genes encoding for crystallins, about a quarter have mutations in genes coding for connexins, with the remainder divided among the genes encoding the heat shock transcription factor-4 (HSF4), aquaporin-0 (AQP0, MIP), and beaded filament structural protein-2 (BFSP2) [3].