The proband was a girl (I) with a heterozygous MKRN3 mutation; her father (II) was a carrier of the mutant allele with no history of CPP; the mother (III) was unaffected; the paternal grandmother (IV) had a history of CPP, whereas the paternal grandfather was unaffected (V). The gene discussed is MKRN3; the disease is central precocious puberty.