To determine whether bone lesion penetrance was variable by sex, we examined μCT scans of femurs from male and female Grk3−/− mice aged 22 months and found that both sexes have high levels of penetrance (87% and 91%, respectively), and that a vast majority of mice with one bone lesion have additional lesions (polyostotic disease) (83%) (Table 1). Here, GRK3 is linked to glycogen storage disease VI.