CAPN3 and Menkes disease: The combined effect of Dmd −/− Capn3 −/− in double-knockout mice, which also presented with a severe MD-phenotype leading to a shortened life-span of ∼13 months (R.B., manuscript in preparation), resulted in spontaneous sarcoma-formation in 44% of the animals with a mean-age of onset of ∼390 days (Figure 1C).