The inheritance pattern in the affected families is consistent with the expression of MKRN3 from the paternally inherited allele only. For example, Patient II-1 in Family A inherited the mutant MKRN3 allele from his mother; because this allele was silenced, he did not have the central precocious puberty phenotype. Patients II-1 in Families C, D, and E were apparently asymptomatic heterozygous carriers of deleterious MKRN3 mutations, but since we were unable to obtain reliable pubertal histories or DNA from their parents, the parental source of their mutations is unknown. Of the 15 patients with central precocious puberty and MKRN3 mutations, 7 were male; this nearly equal sex distribution contrasts with the striking predominance of central precocious puberty in girls that has been reported previously.10 The similar incidence of central precocious puberty in association with MKRN3 mutations in the two sexes in the affected families is consistent with the autosomal pattern of inheritance. In contrast, in the 10 families without mutations in MKRN3, all affected members were female, an incidence that is similar to that reported previously10 (Fig. S1 and Table
