Of the 70 patients with isolated breast development, 39 were diagnosed as having CPP at presentation, with a uterus length of ≥ 35 mm (16/31), a LH/FSH peaks ratio of ≥ 0.66 (25/68) and/or plasma estradiol concentrations ≥ 15 pg/mL (18/67). Here, BRD2 is linked to central precocious puberty.