In a study among school-aged girls in Shanghai, the incidence rate of precocious puberty in 2020 was higher than that in 2016-2019; serum concentrations of MKRN3 (makorin ring finger protein 3, a negative regulator of GnRH) were lower and GnRH concentrations were higher in girls from the 2020 group. The gene discussed is MKRN3; the disease is precocious puberty.