Macedo, DB; Abreu, AP; Reis, AC; Montenegro, LR; Dauber, A; Beneduzzi, D; Cukier, P; Silveira, LF; Teles, MG; Carroll, RS; Guerra Junior, G; Guaragna Filho, G; Gucev, Z; Arnhold, IJ; de Castro, M; Moreira, AC; Martinelli, CE; Hirschhorn, JN; Mendonca, BB; Brito, VN; Antonini, , SR; Kaiser, UB; Latronico, AC
Context: Loss-of-function mutations in makorin ring finger 3 (MKRN3), an imprinted gene located on the long arm of chromosome 15, have been recognized recently as a cause of familial central precocious puberty (CPP) in humans. MKRN3 has a potential inhibitory effect on GnRH secretion. Objectives: To investigate potential MKRN3 sequence variations as well as copy number and methylation abnormalities of the 15q11 locus in patients with apparently sporadic CPP. Setting and participants: We studied 215 unrelated children (207 girls and 8 boys) from three University Medical Centers with a diagnosis of CPP. All but two of these patients (213 cases) reported no family history of premature sexual development. First-degree relatives of patients with identified MKRN3 variants were included for genetic analysis. Main Outcome Measures: All 215 CPP patients were screened for MKRN3 mutations by automatic sequencing. Multiplex ligation-dependent probe amplification was performed in a partially overlapping cohort of 52 patients. Results: We identified five novel heterozygous mutations in MKRN3 in eight unrelated girls with CPP. Four were frameshift mutations predicted to encode truncated proteins and one was a missense mutation, which was suggested to be deleterious by in silico analysis. All patients with MKRN3 mutations had classical features of CPP with a median age of onset at 6 years. Copy number and methylation abnormalities at the 15q11 locus were not detected in the patients tested for these abnormalities. Segregation analysis was possible in 5 of the 8 girls with MKRN3 mutations; in all cases, the mutation was inherited on the paternal allele. Conclusions: We have identified novel inherited MKRN3 defects in children with apparently sporadic CPP, supporting a fundamental role of this peptide in the suppression of the reproductive axis.
