Familial central precocious puberty due to DLK1 deficiency: novel genetic findings and relevance of serum DLK1 levels.

BACKGROUND: Several rare loss-of-function mutations of delta-like noncanonical notch ligand 1 (DLK1) have been described in non-syndromic children with familial central precocious puberty (CPP). OBJECTIVE: We investigated genetic abnormalities of DLK1 gene in a French cohort of children with idiopathic CPP. Additionally, we explored the pattern of DLK1 serum levels in patients with CPP and in healthy children at puberty, as well as in wild-type female mice. PATIENTS AND METHODS: Genomic DNA was obtained from 121 French index cases with CPP. Automated sequencing of the coding region of the DLK1 gene was performed in all cases. Serum DLK1 levels were measured by enzyme linked immunosorbent assay (ELISA) in 209 individuals, including 191 with normal pubertal development and in female mice during postnatal pubertal maturation. RESULTS: We identified 2 rare pathogenic DLK1 allelic variants: A stop gain variant (c.372C>A; p.Cys124X) and a start loss variant (c.2T>G; p.Met1?, or p.0) in 2 French girls with CPP. Mean serum DLK1 levels were similar between healthy children and idiopathic CPP children. In healthy individuals, DLK1 levels correlated with pubertal stage: In girls, DLK1 decreased between Tanner stages III and V, whereas in boys, DLK1 decreased between Tanner stages II and V (P = .008 and .016, respectively). Serum levels of Dlk1 also decreased in wild-type female mice. CONCLUSIONS: Novel loss-of-function mutations in DLK1 gene were identified in 2 French girls with CPP. Additionally, we demonstrated a pattern of dynamic changes in circulating DLK1 serum levels in humans and mice during pubertal stages, reinforcing the role of this factor in pubertal timing.

Novel MKRN3 Missense Mutations Associated With Central Precocious Puberty Reveal Distinct Effects on Ubiquitination.

CONTEXT: Loss-of-function mutations in the maternally imprinted genes, MKRN3 and DLK1, are associated with central precocious puberty (CPP). Mutations in MKRN3 are the most common known genetic etiology of CPP. OBJECTIVE: This work aimed to screen patients with CPP for MKRN3 and DLK1 mutations and analyze the effects of identified mutations on protein function in vitro. METHODS: Participants included 84 unrelated children with CPP (79 girls, 5 boys) and, when available, their first-degree relatives. Five academic medical institutions participated. Sanger sequencing of MKRN3 and DLK1 5' upstream flanking and coding regions was performed on DNA extracted from peripheral blood leukocytes. Western blot analysis was performed to assess protein ubiquitination profiles. RESULTS: Eight heterozygous MKRN3 mutations were identified in 9 unrelated girls with CPP. Five are novel missense mutations, 2 were previously identified in patients with CPP, and 1 is a frameshift variant not previously associated with CPP. No pathogenic variants were identified in DLK1. Girls with MKRN3 mutations had an earlier age of initial pubertal signs and higher basal serum luteinizing hormone and follicle-stimulating hormone compared to girls with CPP without MRKN3 mutations. Western blot analysis revealed that compared to wild-type MKRN3, mutations within the RING finger domain reduced ubiquitination whereas the mutations outside this domain increased ubiquitination. CONCLUSION: MKRN3 mutations were present in 10.7% of our CPP cohort, consistent with previous studies. The novel identified mutations in different domains of MKRN3 revealed different patterns of ubiquitination, suggesting distinct molecular mechanisms by which the loss of MRKN3 results in early pubertal onset.

Gender differences in "social portraits" reflected in MySpace profiles.

The internet has brought about an entirely new method of self-presentation in such online social networking Web sites as MySpace in which individuals create profiles that reflect their identity. This cyber social tool provides a new site of analysis to examine the extent of patterns of gendered identity in which females tend to turn to others for validation in contrast to males, who are more apt to maintain their individuality and whose relationships are more of an extension of their already-complete selves. In this study of 51 female and 49 male MySpace profiles, males were less apt to mention their significant other in the "About Me" section: 43% mentioned their significant other 0 times compared to 16% of females, and 14% of males mentioned their significant other between 2 and 10 times compared to 37% of females (p = 0.003). In the "Interests" section, the majority of males (67%) did not mention their significant other at all compared to 47% of females, and 33% mentioned her between 1 and 5 times compared to 53% of females (p = 0.05). These results reveal that online data sources manifest identity formation consistent with traditional gender roles in which females are dependent on others for their sense of self.