DLK1 Is a Novel Link Between Reproduction and Metabolism.

BACKGROUND: Delta-like homolog 1 (DLK1), also called preadipocyte factor 1, prevents adipocyte differentiation and has been considered a molecular gatekeeper of adipogenesis. A DLK1 complex genomic defect was identified in five women from a single family with central precocious puberty (CPP) and increased body fat percentage. METHODS: We studied 60 female patients with a diagnosis of CPP or history of precocious menarche. Thirty-one of them reported a family history of precocious puberty. DLK1 DNA sequencing was performed in all patients. Serum DLK1 concentrations were measured using an ELISA assay in selected cases. Metabolic and reproductive profiles of adult women with CPP caused by DLK1 defects were compared with those of 20 women with idiopathic CPP. RESULTS: We identified three frameshift mutations of DLK1 (p.Gly199Alafs*11, p.Val271Cysfs*14, and p.Pro160Leufs*50) in five women from three families with CPP. Segregation analysis was consistent with the maternal imprinting of DLK1. Serum DLK1 concentrations were undetectable in three affected women. Metabolic abnormalities, such as overweight/obesity, early-onset glucose intolerance/type 2 diabetes mellitus, and hyperlipidemia, were more prevalent in women with the DLK1 mutation than in the idiopathic CPP group. Notably, the human metabolic alterations were similar to the previously described dlk1-null mice phenotype. Two sisters who carried the p.Gly199Alafs*11 mutation also exhibited polycystic ovary syndrome and infertility. CONCLUSIONS: Loss-of-function mutations of DLK1 are a definitive cause of familial CPP. The high prevalence of metabolic alterations in adult women who experienced CPP due to DLK1 defects suggests that this antiadipogenic factor represents a link between reproduction and metabolism.

Methylome profiling of healthy and central precocious puberty girls.

BACKGROUND: Recent studies demonstrated that changes in DNA methylation (DNAm) and inactivation of two imprinted genes (MKRN3 and DLK1) alter the onset of female puberty. We aimed to investigate the association of DNAm profiling with the timing of human puberty analyzing the genome-wide DNAm patterns of peripheral blood leukocytes from ten female patients with central precocious puberty (CPP) and 33 healthy girls (15 pre- and 18 post-pubertal). For this purpose, we performed comparisons between the groups: pre- versus post-pubertal, CPP versus pre-pubertal, and CPP versus post-pubertal. RESULTS: Analyzing the methylome changes associated with normal puberty, we identified 120 differentially methylated regions (DMRs) when comparing pre- and post-pubertal healthy girls. Most of these DMRs were hypermethylated in the pubertal group (99%) and located on the X chromosome (74%). Only one genomic region, containing the promoter of ZFP57, was hypomethylated in the pubertal group. ZFP57 is a transcriptional repressor required for both methylation and imprinting of multiple genomic loci. ZFP57 expression in the hypothalamus of female rhesus monkeys increased during peripubertal development, suggesting enhanced repression of downstream ZFP57 target genes. Fourteen other zinc finger (ZNF) genes were related to the hypermethylated DMRs at normal puberty. Analyzing the methylome changes associated with CPP, we demonstrated that the patients with CPP exhibited more hypermethylated CpG sites compared to both pre-pubertal (81%) and pubertal (89%) controls. Forty-eight ZNF genes were identified as having hypermethylated CpG sites in CPP. CONCLUSION: Methylome profiling of girls at normal and precocious puberty revealed a widespread pattern of DNA hypermethylation, indicating that the pubertal process in humans is associated with specific changes in epigenetically driven regulatory control. Moreover, changes in methylation of several ZNF genes appear to be a distinct epigenetic modification underlying the initiation of human puberty.

Long-Term Outcomes of Patients with Central Precocious Puberty due to Hypothalamic Hamartoma after GnRHa Treatment: Anthropometric, Metabolic, and Reproductive Aspects.

BACKGROUND: Hypothalamic hamartoma (HH) represents the commonest cause of organic central precocious puberty (CPP). Follow-up of these patients in adulthood is scarce. OBJECTIVE: To describe the anthropometric, metabolic, and reproductive parameters of patients with CPP due to HH before and after treatment with gonadotropin-releasing hormone analog (GnRHa). METHODS: We performed a retrospective and cross-sectional study in a single tertiary center including 14 patients (7 females) with CPP due to HH. RESULTS: The mean duration of GnRHa treatment was 7.7 ± 2.4 years in boys and 7.9 ± 2.1 years in girls. GnRHa treatment was interrupted at the mean chronological age (CA) of 12.1 ± 1.1 years in boys and 10.7 ± 0.5 years in girls. At the last visit, the mean CA of the male and female patients was 21.5 ± 3.2 and 24 ± 3.9 years, respectively. Eleven of the 14 patients reached normal final height (FH) (standard deviation score -0.6 ± 0.9 for males and -0.6 ± 0.5 for females), all of them within the target height (TH) range. The remaining 3 patients had predicted height within the TH range. The mean body mass index and the percentage of body fat mass was significantly higher in females, with a higher prevalence of metabolic disorders. All patients presented normal gonadal function in adulthood, and 3 males fathered a child. CONCLUSION: All patients with CPP due to HH reached normal FH or near-FH. A higher prevalence of overweight/obesity and hypercholesterolemia was observed in the female patients. Finally, no reproductive disorder was identified in both sexes, indicating that HH per se has no deleterious effect on the gonadotropic axis in adulthood.

Assessment of stress levels in girls with central precocious puberty before and during long-acting gonadotropin-releasing hormone agonist treatment: a pilot study.

BACKGROUND: The objective of the study was to determine the stress levels of girls with central precocious puberty (CPP) before and during treatment with a long-acting gonadotropin-releasing hormone agonist (GnRHa). METHODS: The Child Stress Scale (CSS) was used for 10 unrelated girls with CPP before and after the first year of GnRHa treatment. The CSS is divided into four subscales (physical, psychological, psychological with depressive component and psychophysiological reactions). Through a quantitative analysis, it is possible to classify stress into four stages: alarm, resistance, near-exhaustion and exhaustion. RESULTS: At diagnosis, 90% of the girls showed stress levels scores at the alarm or resistance stage on at least one subscale, mostly in terms of physical and psychological reactions. The mean total stress score was significantly higher before when compared to after GnRHa treatment (43.4±15.6 vs. 28.9±9.7; p<0.05). The mean stress scores obtained in all subscales, except the one on psychophysiological reactions, were significantly higher before GnRHa treatment. CONCLUSIONS: Higher stress levels were a common finding in girls with CPP before treatment. The significant stress level reduction after pubertal suppression reinforces the idea that sexual precocity is a stressful condition in children. The CSS might be a useful tool for psychological assessment of patients with CPP.

Paternally Inherited DLK1 Deletion Associated With Familial Central Precocious Puberty.

Context: Central precocious puberty (CPP) results from premature activation of the hypothalamic-pituitary-gonadal axis. Few genetic causes of CPP have been identified, with the most common being mutations in the paternally expressed imprinted gene MKRN3. Objective: To identify the genetic etiology of CPP in a large multigenerational family. Design: Linkage analysis followed by whole-genome sequencing was performed in a family with five female members with nonsyndromic CPP. Detailed phenotyping was performed at the time of initial diagnosis and long-term follow-up, and circulating levels of Delta-like 1 homolog (DLK1) were measured in affected individuals. Expression of DLK1 was measured in mouse hypothalamus and in kisspeptin-secreting neuronal cell lines in vitro. Setting: Endocrine clinic of an academic medical center. Patients: Patients with familial CPP were studied. Results: A complex defect of DLK1 (∼14-kb deletion and 269-bp duplication) was identified in this family. This deletion included the 5' untranslated region and the first exon of DLK1, including the translational start site. Only family members who inherited the defect from their father have precocious puberty, consistent with the known imprinting of DLK1. The patients did not demonstrate additional features of the imprinted disorder Temple syndrome except for increased fat mass. Serum DLK1 levels were undetectable in all affected individuals. Dlk1 was expressed in mouse hypothalamus and in kisspeptin neuron-derived cell lines. Conclusion: We identified a genomic defect in DLK1 associated with isolated familial CPP. MKRN3 and DLK1 are both paternally expressed imprinted genes. These findings suggest a role of genomic imprinting in regulating the timing of human puberty.

High Frequency of MKRN3 Mutations in Male Central Precocious Puberty Previously Classified as Idiopathic.

BACKGROUND/AIMS: Recently, loss-of-function mutations in the MKRN3 gene have been implicated in the etiology of familial central precocious puberty (CPP) in both sexes. We aimed to analyze the frequency of MKRN3 mutations in boys with CPP and to compare the clinical and hormonal features of boys with and without MKRN3 mutations. METHODS: This was a retrospective review of clinical, hormonal and genetic features of 20 male patients with idiopathic CPP evaluated at an academic medical center. The entire coding regions of MKRN3, KISS1 and KISS1R genes were sequenced. RESULTS: We studied 20 boys from 17 families with CPP. All of them had normal brain magnetic resonance imaging. Eight boys from 5 families harbored four distinct heterozygous MKRN3 mutations predicted to be deleterious for protein function, p.Ala162Glyfs*14, p.Arg213Glyfs*73, p.Arg328Cys and p.Arg365Ser. One boy carried a previously described KISS1-activating mutation (p.Pro74Ser). The frequency of MKRN3 mutations among these boys with idiopathic CPP was significantly higher than previously reported female data (40 vs. 6.4%, respectively, p < 0.001). Boys with MKRN3 mutations had typical clinical and hormonal features of CPP. Notably, they had later pubertal onset than boys without MKRN3 abnormalities (median age 8.2 vs. 7.0 years, respectively, p = 0.033). CONCLUSION: We demonstrated a high frequency of MKRN3 mutations in boys with CPP, previously classified as idiopathic, suggesting the importance of genetic analysis in this group. The boys with CPP due to MKRN3 mutations had classical features of CPP, but with puberty initiation at a borderline age.