CHEK2 and breast cancer: For queries on females (8478/10,085, 84.1%; mean age 49.2 [SD 16.1] years; median age 50 [IQR 38-61] years), 79.7% (6757/8478) of the queries were of breast cancer susceptibility genes, and the top 5 genes were BRCA1 (1467/8478, 17.3%), BRCA2 (1449/8478, 17.1%), CHEK2 (895/8478, 10.6%), ATM (548/8478, 6.5%), and PALB2 (402/8478, 4.7%).