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: The objective of the study was 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 eight 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 frame shift 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 five of the eight 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.

Background: Mutations in GLI2 have been associated with holoprosencephaly (HPE), a neuroanatomic anomaly resulting from incomplete cleavage of the developing forebrain, and an HPE-like phenotype involving pituitary anomalies and polydactyly. Objective: To characterise the genotypic and phenotypic findings in individuals with GLI2 variants and clarify clinical findings in individuals with loss-of-function mutations. Methods: Through the National Institutes of Health and collaborating centres, ∼400 individuals with HPE spectrum disorders, endocrine disorders or craniofacial anomalies were screened for GLI2 mutations. Results were combined with all published cases. We compared the clinical and molecular features of individuals with truncating mutations to individuals with variants of unknown significance (defined as not resulting in protein truncation, reported in normal controls and/or deemed unlikely to be pathogenic by functional prediction software). Results: 112 individuals with variants in GLI2 were identified, with 43 having truncating mutations. Individuals with truncating mutations were more likely to have both pituitary anomalies and polydactyly versus those with variants of unknown significance (p<0.0001 by Fisher’s exact test); only 1 of 43 had frank HPE. These individuals were more likely to have recognised penetrance (polydactyly or pituitary anomalies or both) than those without truncating mutations (p=0.0036 by Fisher's exact test). A common facial phenotype was seen in individuals (with midface hypoplasia, cleft lip/palate and hypotelorism) with truncating mutations. Conclusions: Individuals with truncating mutations in GLI2 typically present with pituitary anomalies, polydactyly and subtle facial features rather than HPE. This will be helpful in screening populations for GLI2 mutations and for counselling affected patients. Trial registration: 98-HG-0249/04-HG-0093.

CTNNB1/β-catenin mutations and activation of Wnt/β-catenin pathway are frequent in adult adrenocortical tumors (ACT), but data on childhood ACT are lacking. The aim of the study was to investigate the presence of Wnt/β-catenin pathway abnormalities in childhood ACT. Clinicopathological findings and outcome of 62 childhood ACT patients were analyzed regarding CTNNB1 mutations and the expression of Wnt-related genes (CTNNB1; WNT4, a Wnt ligand; SFRP1, DKK3, and AXIN1, Wnt inhibitors; TCF7, a transcription factor; and MYC and WISP2, target genes) by quantitative PCR and immunohistochemistry. CTNNB1-activating mutations were found in only four of 62 ACT (6%), all of them harboring TP53 mutation. There was association between the presence of CTNNB1 mutations and death (P = 0.02). Diffuse β-catenin accumulation was found in 71% of ACT, even in ACT without CTNNB1 mutations. Compared to normal adrenals, ACT presented increased expression of CTNNB1 (P = 0.008) and underexpression of Wnt inhibitor genes: DKK3 (P < 0.0001), SFRP1 (P = 0.05), and AXIN1 (P = 0.04). With regard to Wnt/β-catenin target genes, ACT presented increased expression of WISP2 but lower expression of MYC. Higher overall survival was associated with underexpression of SFRP1 (P = 0.01), WNT4 (P = 0.004), and TCF7 (P < 0.01). CTNNB1 mutations are not common in childhood ACT but appear to associate with poor prognosis. Nevertheless, most ACT exhibit increased expression of β-catenin and WISP2 and reduced expression of Wnt inhibitor genes (DKK3, SFRP1, and AXIN1). Thus, in addition to CTNNB1 mutations, other genetic events affecting the Wnt/β-catenin pathway may be involved in childhood adrenocortical tumorigenesis.

Inhibition of the Tcf/beta-catenin complex increases apoptosis and impairs adrenocortical tumor cell proliferation and adrenal steroidogenesis