HEXA and Sandhoff disease: Murine models of the related GM2-ganglioside storage disorders, Tay-Sachs and Sandhoff disease, in which the Hexa and Hexb genes are disrupted, respectively, have been reported to display marked accumulation of vacuoles in cells of the epididymis [78], [79], which appear strikingly similar to those we observed in our JNCL model.