POLG2 and calcification: Further analysis of all 85 G2 mice and 138 G3 mice revealed that 84% of G2 mice with renal calcification, and 71% of G3 mice with renal calcification had the Tyr265Stop Polg2 mutation (Table 1), indicating that the mutation, which co‐segregates with the phenotype (Table 1), had a reduced penetrance.