While ATM was the most commonly lost HRR gene in ovarian, breast, and other cancers, and occurred at a rate similar to BRCA1/2- deficiency, HRD+ calls were enriched only in the HRD-DNA model, suggesting that ATM loss may be uniquely associated with a high gwLOH phenotype in breast and ovarian cancer but not HRD in other cancer types. The gene discussed is BRCA1; the disease is ovarian cancer.