Although mean spontaneous serum FSH concentrations were greater in children with central precocious puberty (p < 0.005) and provided fair sensitivity and specificity, subjects in groups A and B had predominant FSH responses to leuprolide challenge and mean stimulated serum FSH concentrations in girls with premature thelarche were higher than pubertal children at both 1 and 3 h (P < 0.005). The gene discussed is BRD2; the disease is central precocious puberty.