TSC2 and kidney disorder: Based on observations regarding strain differences reported in Onda et al. 1999 [60], we backcrossed the Tsc2+/- genotype onto A/J and C57BL/6 backgrounds, compared kidney disease severity, and found that the A/J strain shows a much higher kidney tumor burden than mice in the C57BL/6 background at 9 and 12 months of age as shown by the average score per kidney and average number of cystadenomas per kidney.