In the girls with precocious breast development, the increases in the LH and FSH plasma concentrations in response to a GnRH test excludes a peripheral origin, as we observed during the study period in two patients with ovarian granulosa cell tumor [2], in five patients with McCune-Albright syndrome and in 11 with isolated ovarian cyst [25]. Here, GNRH1 is linked to ovarian granulosa cell tumor.