BRCA2 and posterior cortical atrophy: By contrast, for BRCA2 carriers the SIR was higher for GS ≥ 7 (SIR 5.07, 95% CI 3.20–8.02) than for GS ≤ 6 PCa (SIR 3.03, 95% CI 1.24–7.44; Table 4).