PALB2 and breast cancer: For patients aged 45 years or less (early-onset breast cancer patients, n = 288), a total of 51 variants were detected in 50 (50/288, 17.4%) patients, followed by BRCA2 (45.1%, 23/51), BRCA1 (35.3%, 18/51), PALB2 (7.8%, 4/51), TP53 (5.9%, 3/51), and other genes (5.9%, 3/51).