Genetic determinants of pubertal timing in the general population

Time-varying associations of gestational and childhood triclosan with pubertal and adrenarchal outcomes in early adolescence

Background

Triclosan is an endocrine-disrupting chemical, but associations with pubertal outcomes remain unclear. We examined associations of gestational and childhood triclosan with adolescent hormone concentrations and pubertal stage.

Methods

We quantified urinary triclosan concentrations twice during pregnancy and seven times between birth and 12 years in participants recruited from Cincinnati, OH (2003-2006). We averaged concentrations across pregnancy and childhood and separately considered individual exposure periods in multiple informant models. At 12 years, we measured serum hormone concentrations (males [n = 72] and females [n = 84]-dehydroepiandrosterone-sulfate, luteinizing hormone, follicle-stimulating hormone; males-testosterone; females-estradiol). Also at age 12 years, participants self-reported physical development and menarchal timing. We estimated associations (95% confidence interval) of triclosan with hormone concentrations, more advanced physical development, and age at menarche.

Results

For females, each doubling of childhood triclosan was associated with 16% lower estradiol concentrations (-29%, 0%), with stronger associations for measures closer to adolescence. We found suggestive evidence that higher triclosan at any age was associated with ~10% (for gestational triclosan: -18%, -2%) lower follicle-stimulating hormone concentrations among males and early postnatal (1-3 years) triclosan was associated with 63% (5%, 96%) lower odds of advanced pubic hair development in females. In multiple informant models, each doubling of gestational triclosan concentrations was associated with 5% (0%, 9%) earlier age at menarche, equivalent to 5.5 months.

Conclusion

Gestational and childhood triclosan concentrations were related to some pubertal outcomes including hormone concentrations and age at menarche. Our findings highlight the relevance of elucidating potential sex-specific and time-dependent actions of triclosan.

Central precocious puberty: a review of diagnosis, treatment, and outcomes

Central precocious puberty (CPP) refers to early activation of the hypothalamic-pituitary-gonadal (HPG) axis and is manifested by breast development in girls or testicular enlargement in boys before the normal physiological age ranges. CPP can be precipitated by intracranial pathology, exposure to high levels of sex steroids, or environmental risk factors, but most cases are idiopathic. Monogenic causes have also been identified. In this Review, we summarise pathophysiology, risk factors, diagnosis, and management of CPP. Concern for CPP should prompt referral to paediatric endocrinology where diagnosis is confirmed by clinical, biochemical, radiological, and genetic testing. CPP is treated with a gonadotropin-releasing hormone analogue, the primary aims of which are to increase adult height and postpone development of secondary sexual characteristics to an age that is more commensurate with peers. Although long-term outcomes of treatment with gonadotropin-releasing hormone analogues are reassuring, additional research on the psychological effect of CPP is needed.

Sexual maturation of HIV-infected and uninfected male children in Abakaliki, South-East, Nigeria: a cross-sectional study

INTRODUCTION

HIV infection, through various mechanisms causes a derangement in sexual maturation. This study compared the Marshal and Tanner staging of HIV-infected and uninfected males. The aim of the study was to determine the sexual maturation in male children infected with HIV on HAART in Abakaliki.

METHODS

this was a cross-sectional and comparative study involving 80 HIV-infected boys aged 8-17 years and 80 uninfected counterparts matched for age and socio-economic class. Stages of sexual maturation (testicular size and pubic hair) were determined according to the method proposed by Marshall and Tanner. The testicular size was measured using an orchidometer. Data analysis was done with SPSS version 20. Structured questionnaire was used to collect information on socio-demographics.

RESULTS

assessment of pubic hair development, showed that 45 (56.2%) of the subjects were in the pre-pubertal stage compared to 27 (33.8%) among the controls, this relationship was statistically significant (p=0.005, OR = 2.5, C.I=1.3-4.8). The mean testicular volume among subjects was found to be 8.29 ± 8.26mls compared to 11.57 ± 8.26mls found in controls. This relationship was also statistically significant. There were significant statistical relationships between duration on HAART and clinical stages of disease with both pubic hair development and testicular volume of subjects and controls.

CONCLUSION

HIV-infected males had significantly delayed onset and progression of sexual maturation. Routine assessment of the sexual maturation of HIV-infected children as well as addressing the modifiable variables influencing sexual maturity is recommended.

Transcriptome Sequencing-Based Mining of Genes Associated With Pubertal Initiation in Dolang Sheep

Improving the fertility of sheep is an important goal in sheep breeding as it greatly increases the productivity. Dolang sheep is a typical representative breed of lamb in Xinjiang and is the main local sheep breed and meat source in the region. To explore the genes associated with the initiation of puberty in Dolang sheep, the hypothalamic tissues of Dolang sheep prepubertal, pubertal, and postpubertal periods were collected for RNA-seq analysis on the Illumina platform, generating 64.08 Gb clean reads. A total of 575, 166, and 648 differentially expressed genes (DEGs) were detected in prepuberty_vs._puberty, postpuberty_vs._prepuberty, and postpuberty_vs._puberty analyses, respectively. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, the related genes involved in the initiation of puberty in Dolang sheep were mined. Ten genes that have direct or indirect functions in the initiation of puberty in Dolang sheep were screened using the GO and KEGG results. Additionally, quantitative real-time PCR was used to verify the reliability of the RNA-Seq data. This study provided a new approach for revealing the mechanism of puberty initiation in sheep and provided a theoretical basis and candidate genes for the breeding of early-pubertal sheep by molecular techniques, and at the same time, it is also beneficial for the protection, development, and utilization of the fine genetic resources of Xinjiang local sheep.

A review of the genetics and epigenetics of central precocious puberty

Gonadotrophin dependent sexual precocity, commonly referred to as central precocious puberty (CPP), results from a premature reactivation of the hypothalamic-pituitary-gonadal (HPG) axis before the normal age of pubertal onset. CPP is historically described as girls who enter puberty before the age of eight, and boys before the age of nine. Females are more likely to be diagnosed with idiopathic CPP; males diagnosed with CPP have a greater likelihood of a defined etiology. These etiologies may include underlying CNS congenital defects, tumors, trauma, or infections as well as environmental, genetic, and epigenetic factors. Recently, genetic variants and mutations which may cause CPP have been identified at both the level of the hypothalamus and the pituitary. Single nucleotide polymorphisms (SNPs), monogenetic mutations, and modifications of the epigenome have been evaluated in relationship to the onset of puberty; these variants are thought to affect the development, structure and function of GnRH neurons which may lead to either precocious, delayed, or absent pubertal reactivation. This review will describe recent advances in the field of the genetic basis of puberty and provide a clinically relevant approach to better understand these varying etiologies of CPP.

Gene Polymorphisms Associated with Central Precocious Puberty and Hormone Levels in Chinese Girls

Central precocious puberty (CPP) is associated with adverse health outcomes in females; however, CPP pathogenesis remains unclear. In this study, we investigated the association of 20 single nucleotide polymorphisms (SNPs) in eight genes with CPP risk and hormone levels. A case-control study on 247 and 243 girls with and without CPP, respectively, was conducted at Kunming Children's Hospital, China, from September 2019 to August 2020. The genotype of the SNPs and their haplotypes were identified. Additionally, the effects of the polymorphisms on hormone levels were investigated. Three variants (rs10159082, rs7538038, and rs5780218) in KISS1 and two variants (rs7895833 and rs3758391) in SIRT1 were related to an increased CPP risk (odds ratio (OR) = 1.524, 1.507, 1.409, 1.348, and 1.737; 95% confidence interval (CI) = 1.176-1.974, 1.152-1.970, 1.089-1.824, 1.023-1.777, and 1.242-2.430, respectively). Rs3740051in SIRT1 and rs1544410 in VDR reduced CPP risk (OR = 0.689, 0.464; 95% CI, 0.511-0.928, 0.232-0.925, respectively). Rs1544410, rs7975232, and rs731236 in VDR were negatively correlated with peak follicle-stimulating hormone (FSH; β = -2.181; P=0.045), basal FSH (β = -0.391; P=0.010), and insulin-like growth factor (β = -50.360; P=0.041) levels, respectively. KISS1, SIRT1, and VDR variants were associated with CPP susceptibility, and VDR SNPs influenced hormonal levels in Chinese females with CPP. In particular, VDR polymorphism rs1544410 was associated with both CPP risk and GnRH-stimulated peak FSH levels. Further functional research and large-scale genetic studies of these loci and genes are required to confirm our findings.

Timing of Puberty and Late Pubertal Height in Saudi Schoolboys: Riyadh Puberty Study II

OBJECTIVE

Puberty has a significant contribution to the final height. Therefore, it is crucial to understand the normal variations in the onset and tempo of puberty in a specific population. In this study, we aimed to provide normative data on the timing of puberty and late pubertal height (LPH) in Saudi schoolboys in Riyadh.

METHODS

This is a cross-sectional field study (2011-2013) including Saudi schoolboys (grades 1-12; aged 6 to 19 years). Schools were chosen to represent the population from urban and rural areas in the Riyadh region. Pubertal maturity staging for gonads was assessed by measuring testicular size using a Prader orchidometer and assessing the Tanner staging of pubic hair. The marginal mean age was calculated using regression analysis.

RESULTS

We recruited 1086 schoolboys. The estimated mean age of pubertal onset at G2 was 11.8 (95% CI 11.60-12.0) years, for gonadal development at G3 was 13.2 (95% CI 12.9-13.5), G4 = 15.0 (95% CI 14.7-15.2), and G5 = 16.1 (95% CI 15.9-16.3) years, and for pubic hair stage 2 (PH2) was 12.6 (95% CI 12.4-12.9) years. The estimated time from G2/PH2 to G5/PH5 was 4.3 and 3.9 years, respectively. At the onset of puberty, the mean height was 144.7 cm and it reached 167.8 cm at G5 with a pubertal height gain of 23.1 cm.

CONCLUSION

Our data present the norms of the timing of puberty and LPH in Saudi schoolboys. Saudi adolescent males are shorter than some European and American comparatives mainly due to shortness during childhood. However, they could have shorter LPH than Turkish, Greek, Thai, and Japanese due to a less pubertal height gain.

Genetic Etiology of Idiopathic Hypogonadotropic Hypogonadism

Idiopathic hypogonadotropic hypogonadism (IHH) is a group of rare developmental disorders characterized by low gonadotropin levels in the face of low sex steroid hormone concentrations. IHH is practically divided into two major groups according to the olfactory function: normal sense of smell (normosmia) nIHH, and reduced sense of smell (hyposmia/anosmia) Kallmann syndrome (KS). Although mutations in more than 50 genes have been associated with IHH so far, only half of those cases were explained by gene mutations. Various combinations of deleterious variants in different genes as causes of IHH have been increasingly recognized (Oligogenic etiology). In addition to the complexity of inheritance patterns, the spontaneous or sex steroid-induced clinical recovery from IHH, which is seen in approximately 10–20% of cases, blurs further the phenotype/genotype relationship in IHH, and poses challenging steps in new IHH gene discovery. Beyond helping for clinical diagnostics, identification of the genetic mutations in the pathophysiology of IHH is hoped to shed light on the central governance of the hypothalamo-pituitary-gonadal axis through life stages. This review aims to summarize the genetic etiology of IHH and discuss the clinical and physiological ramifications of the gene mutations.

Delayed age at menarche in chronic respiratory diseases

OBJECTIVE

Age at menarche (AAM) is an important indicator of physiological development in women, and delayed AAM has been associated with chronic illnesses. We investigated predictive factors at diagnosis that influence AAM in adolescents with chronic respiratory diseases.

STUDY DESIGN

AAM was assessed in 1207 northern Italian female aged 11-24 (1062 healthy, 98 with asthma and 47 with cystic fibrosis [CF]). AAM was defined by recall and status quo methods. We studied anthropometric data, metabolic status, diagnosis parameters, presence of irregular menses. Clinical data of subjects with chronic respiratory illness were compared with that of healthy adolescents.

RESULTS

Mean AAM for healthy adolescents was 12.49 ± 1.2 years. Mother's AAM was positively associated with that of their daughters (P < .001). BMI was negatively correlated with AAM (P < .001). 69% of healthy adolescents referred regular menses. AAM in the different groups was 12.79 ± 3.0 years for patients with asthma (P < .05 vs healthy) and 13.24 ± 1.44 years for adolescents with CF (P < .0001 vs healthy). In the asthmatic group, 57% of the patients referred regular menses, and no significant differences were found between AAM and control of the disease (ACT test). In the CF group, no correlation was found between the type of CFTR mutation or FEV1% and AAM. 53% of the patients with CF referred regular menses.

CONCLUSIONS

AAM in patients with CF and asthma was significantly higher than in healthy adolescents, and menses abnormalities were observed in the last two groups. Inflammation influences the reproductive function in chronic respiratory disease.

ESR1 gene polymorphism (rs827421) as a potential genetic marker for constitutional delay of growth and puberty in Egyptian adolescents

Constitutional delay of growth and puberty (CDGP) is a variant of normal pubertal timing and progress. It is the most common form of delayed puberty in both genders. The genetic director of CDGP is ill-understood despite the positive family history result noted in those patients. The current study aimed at assessing the role of estrogen receptor 1 (ESR1) gene variant (rs827421) in Egyptian adolescents with CDGP. A cross-sectional study with follow-up part was carried out on 6760 children aged 4 to15 years. The study focused generally on children aged 13-15 years in order to evaluate the prevalence of delayed puberty in relation to all ages in general and to their peers in specific. Assessment of serum TSH, FSH, and LH was conducted on all participants, along with the measurement of serum-free testosterone for males and estradiol for females. Genotyping of ESR1 (rs827421) was done to all subjects through the use of TaqMan discrimination assay by real-time PCR. ESR1 (rs827421) GG genotype and G allele were significantly dominant among CDGP adolescents in comparison with controls (OR = 25.67 and 6.90). As regards follow-up of testicular size, AA genotype was significantly associated with increased size in the right and left testis compared to other genotypes (P = 0.021 and 0.006, respectively). Moreover, AA genotype showed significantly higher Tanner stage in both males and females in comparison with other genotypes. Serum estradiol level was significantly higher in AA genotype group than other genotypes groups. ESR1 gene polymorphism can be considered a potential genetic marker for CDGP in both sexes in a sample of Egyptian adolescents.

Association between factors related to the pregnancy, neonatal period, and later complications (especially asthma) and menarcheal age in a sample of Lebanese girls

BACKGROUND

Studies about the majority of the factors that may potentially influence the pubertal timing and menarche were controversial. The objective was to evaluate the association between factors related to the pregnancy, neonatal period, and the complications that may happen later in life and the menarcheal age in a sample of Lebanese girls admitted or not to the NICU at birth. Our secondary objective was to try to find, for the first time in literature, a correlation between respiratory distress at birth and the need of oxygen therapy with the age of the first menses in these girls.

METHODS

It is a cross-sectional retrospective study, conducted between January and March 2019. Our sample included all the 2474 girls born in Notre-Dame-de-Secours hospital, between 2000 and 2005; the sample consisted of 297 girls (97 girls admitted to the NICU and 200 randomly chosen to participate in our study with a ratio of 1:2 (1 girl admitted to the NICU vs 2 girls born in the nursery).

RESULTS

Asthma later in life was significantly associated with lower age at menarche in girls, whereas a higher mother's age at menarche and a higher gestational age were significantly associated with higher age at menarche in girls. When taking each cause of NICU admission as an independent variable, showed that a higher mother's age at menarche was significantly associated with higher age at menarche in girls, whereas a higher number of days of phototherapy, a preeclampsia in the mother during pregnancy and asthma later in life in the girl were significantly associated with a lower age at menarche in girls.

CONCLUSION

The timing of menarche seems to be associated with many factors in Lebanese girls that should not be disregarded by physicians.

Timing of pubertal development in boys born with cryptorchidism and hypospadias: a nationwide cohort study

Pubertal development may be altered in boys with cryptorchidism and hypospadias, but existing knowledge is inconsistent. Therefore, we investigated the association between cryptorchidism and hypospadias and pubertal development in a large cohort study. Boys in the Puberty Cohort, a cohort nested within the Danish National Birth Cohort, were included in this study. Information on cryptorchidism and hypospadias was retrieved from the Danish National Patient Register. From 11 years until 18 years or full pubertal development, information on physical markers of pubertal development was provided biannually, including Tanner stages, axillary hair, acne, voice break, and first ejaculation. In multivariate regression models for interval censored data, the mean (95% confidence intervals [CIs]) differences in months in obtaining the pubertal markers between boys with and without the anomalies were estimated. Among 7698 boys, 196 (2.5%) had cryptorchidism and 60 (0.8%) had hypospadias. Boys with hypospadias experienced first ejaculation and voice break 7.7 (95% CI: 2.5-13.0) months and 4.5 (95% CI: 0.3-8.7) months later than boys without hypospadias. The age at attaining the Tanner stages for gonadal and pubic hair growth was also higher, though not statistically significant. Pubertal development seemed unaffected in boys with mild as well as severe cryptorchidism. In conclusion, hypospadias may be associated with delayed pubertal development, but pubertal development seems unaffected by cryptorchidism. The relation between hypospadias and later pubertal development may be due to the underlying shared in utero risk or genetic factors.

Body mass index growth trajectories, early pubertal maturation, and short stature

BACKGROUND

Childhood body mass index (BMI) trajectory classes are rarely linked to early puberty risk, particularly among Chinese children. We estimated early puberty risk across BMI trajectory classes, investigated factors contributing to pubertal development, and examined differences in final adult height between children exhibiting early and nonearly pubertal maturation across the classes.

METHODS

The Taiwan Children Health Study recruited 10-year-old children in 2010 from 14 Taiwanese communities and resurveyed them at age 11, 12, and 18 years. The study comprised 3109 children (50.4% boys) with available data for BMI (age 6-11 years) and pubertal stages (age 11, 12, and 18 years).

RESULTS

Classes 1-4 were persistently healthy weight, rapid BMI growth, chronically overweight/obese, and early transient overweight/obese. Children in class 3 exhibited the highest risk of early pubertal maturation. Puberty genetic score, low sleep quality, and high fat-free mass collectively explained 15% of the variance in Tanner stages among class 3 children. Early pubertal maturation was considered to cause short and tall stature in boys and girls, respectively.

CONCLUSIONS

Modifying sleep quality and fat-free mass may reduce early puberty risk in children with chronic overweight/obesity. Vigorous physical activity may reduce adiposity and increase the final adult height in the children.

The analysis of endocrine disruptors in patients with central precocious puberty

Background

A few studies have reported a positive association between phthalate exposure and pubertal timing, but several conflicting reports exist. The main objective of the study was to determine whether phthalate exposure was associated with central precocious puberty in girls.

Methods

This was a multicenter case-control study wherein 47 girls with central precocious puberty (CPP) and 47 controls (26 pre-pubertal girls and 21 pubertal girls) were enrolled. No obese girls were included. Five phthalate metabolites (creatinine adjusted) and bisphenol A (BPA) were measured in the first spot urine samples of these 94 girls in the early morning.

Results

The median values of monobenzyl phthalate (MBzP), mono-2-ethyl-5-carboxypentyl phthalate (MECPP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and mono-n-butyl phthalate (MnBP) were 3.1, 29.3, 18.0, 15.4, and 25.2 μg/g creatinine in the CPP group, 4.3, 53.7, 35.7, 29.1, and 66.0 μg/g creatinine in the pre-pubertal control group, and 1.7, 28.7, 21.4, 12.1, and 33.3 μg/g creatinine in the pubertal control group, respectively.

The urinary concentration of the five phthalates was significantly lower in the CPP group than in the pre-pubertal control group (P < 0.001). Conversely, there was no significant difference in the urinary concentration of the five phthalates between the CPP and pubertal control groups (P values: 0.077 for MBzP, 0.733 for MECPP, 0.762 for MEHHP, 0.405 for MEOHP, and 0.981 for MnBP). In addition, the BPA level was not significantly different between the CPP and pubertal control groups (BPA median values: 0.63 μg/g creatinine, the CPP group; 1.7 μg/g creatinine, the pubertal control group; P value = 0.092).

Conclusions

Our study showed that there was no significant difference in the urinary phthalate levels between the CPP and pubertal control groups. Moreover, phthalate metabolites were significantly lower in the CPP group than in the pre-pubertal control group. Further investigation about endocrine disruptors and pubertal progression is needed.

The Makorin lep-2 and the lncRNA lep-5 regulate lin-28 to schedule sexual maturation of the C. elegans nervous system

Sexual maturation must occur on a controlled developmental schedule. In mammals, Makorin3 (MKRN3) and the miRNA regulators LIN28A/B are key regulators of this process, but how they act is unclear. In C. elegans, sexual maturation of the nervous system includes the functional remodeling of postmitotic neurons and the onset of adult-specific behaviors. Here, we find that the lin-28-let-7 axis (the 'heterochronic pathway') determines the timing of these events. Upstream of lin-28, the Makorin lep-2 and the lncRNA lep-5 regulate maturation cell-autonomously, indicating that distributed clocks, not a central timer, coordinate sexual differentiation of the C. elegans nervous system. Overexpression of human MKRN3 delays aspects of C. elegans sexual maturation, suggesting the conservation of Makorin function. These studies reveal roles for a Makorin and a lncRNA in timing of sexual differentiation; moreover, they demonstrate deep conservation of the lin-28-let-7 system in controlling the functional maturation of the nervous system.

Clinical Management of Congenital Hypogonadotropic Hypogonadism

The initiation and maintenance of reproductive capacity in humans is dependent on pulsatile secretion of the hypothalamic hormone GnRH. Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder that results from the failure of the normal episodic GnRH secretion, leading to delayed puberty and infertility. CHH can be associated with an absent sense of smell, also termed Kallmann syndrome, or with other anomalies. CHH is characterized by rich genetic heterogeneity, with mutations in >30 genes identified to date acting either alone or in combination. CHH can be challenging to diagnose, particularly in early adolescence where the clinical picture mirrors that of constitutional delay of growth and puberty. Timely diagnosis and treatment will induce puberty, leading to improved sexual, bone, metabolic, and psychological health. In most cases, patients require lifelong treatment, yet a notable portion of male patients (∼10% to 20%) exhibit a spontaneous recovery of their reproductive function. Finally, fertility can be induced with pulsatile GnRH treatment or gonadotropin regimens in most patients. In summary, this review is a comprehensive synthesis of the current literature available regarding the diagnosis, patient management, and genetic foundations of CHH relative to normal reproductive development.

Interdisciplinary Work Is Essential for Research on Puberty: Complexity and Dynamism in Action

Puberty is associated with changes in behavior and psychosocial well-being, and is important in lifelong health. We present five different facets regarding interdisciplinary research that are important to puberty. A short history of philosophical issues instrumental in promoting early interdisciplinary research is first presented. We discuss then what is hard and what is easy about interdisciplinary research, the purpose of which is to alert scientists to challenges and opportunities for interdisciplinary research on puberty. Readers then are introduced to advances and obstacles in interdisciplinary research on development. Recommendations for tailoring graduate education toward interdisciplinarity are introduced. Finally, issues related to publication, education of scientists, and policy makers are described. The report concludes with a discussion of funding and policy issues.

A novel familial 9q31.2q32 microdeletion: Muscle cramping, somnolence, fatigue, sensorineural hearing loss, pubertal delay, and short stature

We report a novel 9q31.2q32 (chr9: 109195179-113974353, hg 18) microdeletion characterized by fatigue, muscle cramps, short stature, delayed puberty, sensorineural hearing loss, and mild developmental delay. Overlapping microdeletions reported in this region also demonstrate facial dysmorphism, skeletal anomalies, cleft palate, and cardiac valvular abnormalities. In comparing these cases, we suggest critical region of chr9: 109711873-113407621 (hg 18).

Physiology of puberty in boys and girls and pathological disorders affecting its onset

Puberty is a physiological event involving the attainment of reproductive capability and complete development of sexual and physical organs. Changing from childhood to adulthood is a complex process and is tightly controlled by interconnection pathways at the level of the hypothalamus which can be influenced by environmental, psychosocial, and endocrine factors. Although various mechanisms underlying the onset of normal puberty have been investigated in humans and animals, the exact molecular mechanisms thereof remain unclear. The aim of this review is to summarize the current state of knowledge and provide a synoptic overview about the physiology of puberty in adolescent boys and girls, and describe pathological disorders affecting its onset.

Transient modification of lin28b expression - Permanent effects on zebrafish growth

Recent genome-wide association studies and mouse models have identified LIN28B as a gene affecting several pubertal timing-related traits and vertebrate growth. However, the exact biological mechanisms underlying the associations remain unknown. We have explored the mechanisms linking LIN28B with growth regulation by combining human gene expression data with functional models. Specifically, we show that 1) pubertal timing-associated genetic variation correlates with LIN28B expression in the pituitary and hypothalamus, 2) downregulating lin28b in zebrafish embryos associates with aberrant development of kiss2-neurons, and 3) increasing lin28b expression transiently by synthetic mRNA injections during embryogenesis results in sustained enhancement of zebrafish growth. Unexpectedly, the mRNA injections resulted in advanced sexual maturation of female fish, suggesting that lin28b may influence pubertal timing through multiple developmental mechanisms. Overall, these results provide novel insight into LIN28B function in vertebrate growth regulation, emphasizing the importance of the gene and related genetic pathways for embryonic and juvenile development.

MKRN3 Interacts With Several Proteins Implicated in Puberty Timing but Does Not Influence GNRH1 Expression

Paternally-inherited loss-of-function mutations in makorin ring finger protein 3 gene (MKRN3) underlie central precocious puberty. To investigate the puberty-related mechanism(s) of MKRN3 in humans, we generated two distinct bi-allelic MKRN3 knock-out human pluripotent stem cell lines, Del 1 and Del 2, and differentiated them into GNRH1-expressing neurons. Both Del 1 and Del 2 clones could be differentiated into neuronal progenitors and GNRH1-expressing neurons, however, the relative expression of GNRH1 did not differ from wild type cells (P = NS). Subsequently, we investigated stable and dynamic protein-protein interaction (PPI) partners of MKRN3 by stably expressing it in HEK cells followed by mass spectrometry analyses. We found 81 high-confidence novel protein interaction partners, which are implicated in cellular processes such as insulin signaling, RNA metabolism and cell-cell adhesion. Of the identified interactors, 20 have been previously implicated in puberty timing. In conclusion, our stem cell model for generation of GNRH1-expressing neurons did not offer mechanistic insight for the role of MKRN3 in puberty initiation. The PPI data, however, indicate that MKRN3 may regulate puberty by interacting with other puberty-related proteins. Further studies are required to elucidate the possible mechanisms and outcomes of these interactions.

Cloning and expression of lin-28 homolog B gene in the onset of puberty in Duolang sheep

Objective

Recent studies have demonstrated that lin-28 homolog B (LIN28B)/miRNA let-7 (let-7) plays a role in the regulation of pubertal onset in mammals. However, the role of LIN28B/let-7 in the onset of ovine puberty remains unknown. We cloned the Duolang sheep Lin28B cDNA sequence, detected the expression change of LIN28B, let-7a and let-7g in hypothalamus, pituitary and ovary tissues at three different pubertal stages.

Methods

The reverse transcriptase polymerase chain reaction (RT-PCR) was used to clone the cDNA sequence of LIN28B gene from Duolang sheep and the bioinformatics methods were applied to analyze the amino acid sequence of LIN28B protein. The mRNA expression levels of the LIN28B gene at different pubertal stages were examined by real time RT-PCR.

Results

LIN28B cDNA of Duolang sheep was cloned, and two transcripts were obtained. The amino acid sequence of transcript 1 shares 99.60%, 98.78%, and 94.80% identity with those of goat, wild yak and pig, respectively. Strong LIN28B mRNA expression was detected in the hypothalamus, pituitary, ovary, oviduct and uterus, while moderate expression was found in the liver, kidney, spleen and heart, weak expression was observed in the heart. No expression was found in the lungs. Quantitative real-time PCR (QPCR) and western-blot analysis revealed that the LIN28B was highly expressed in the hypothalamus and ovary at prepuberty stages, and this expression significantly decreased from the prepuberty to puberty stages (p<0.05). Markedly increased levels of mRNA expression were detected in the pituitary from prepuberty to puberty (p<0.05) and then significantly decreased from puberty to postpuberty (p<0.05). The expression levels of let-7a and let-7g showed no significant changes among different pubertal stages (p>0.05).

Conclusion

These results provided a foundation for determining the functions of LIN28B/let-7 and their role in the onset of sheep puberty.

SIRT1 mediates obesity- and nutrient-dependent perturbation of pubertal timing by epigenetically controlling Kiss1 expression

Puberty is regulated by epigenetic mechanisms and is highly sensitive to metabolic and nutritional cues. However, the epigenetic pathways mediating the effects of nutrition and obesity on pubertal timing are unknown. Here, we identify Sirtuin 1 (SIRT1), a fuel-sensing deacetylase, as a molecule that restrains female puberty via epigenetic repression of the puberty-activating gene, Kiss1. SIRT1 is expressed in hypothalamic Kiss1 neurons and suppresses Kiss1 expression. SIRT1 interacts with the Polycomb silencing complex to decrease Kiss1 promoter activity. As puberty approaches, SIRT1 is evicted from the Kiss1 promoter facilitating a repressive-to-permissive switch in chromatin landscape. Early-onset overnutrition accelerates these changes, enhances Kiss1 expression and advances puberty. In contrast, undernutrition raises SIRT1 levels, protracts Kiss1 repression and delays puberty. This delay is mimicked by central pharmacological activation of SIRT1 or SIRT1 overexpression, achieved via transgenesis or virogenetic targeting to the ARC. Our results identify SIRT1-mediated inhibition of Kiss1 as key epigenetic mechanism by which nutritional cues and obesity influence mammalian puberty.

The onset of mammalian puberty is sensitive to metabolic changes and nutritional status, but the mechanisms underlying this phenomenon are poorly understood. Here the authors show that the epigenetic regulator of transcription, SIRT1, mediates the effects of under and overnutrition on pubertal timing by controlling the expression of Kiss1 in hypothalamic neurons.

Delayed puberty versus hypogonadism: a challenge for the pediatrician

Constitutional delay of growth and puberty (CDGP) is the most common cause of delayed puberty (DP), is mainly found in males, and is characterized by short stature and delayed skeletal maturation. A family history of the subject comprising the timing of puberty in the parents and physical examination may provide clues regarding the cause of DP. Delayed onset of puberty is rarely considered a disease in either sex. In fact, DP usually represents a common normal variant in pubertal timing, with favorable outcomes for final height and future reproductive capacity. In adolescents with CDGP, a linear growth delay occurs until immediately before the start of puberty, then the growth rate rapidly increases. Bone age is often delayed. CDGP is a diagnosis of exclusion; therefore, alternative causes of DP should be considered. Functional hypogonadotropic hypogonadism may be observed in patients with transient delay in hypothalamic-pituitary-gonadal axis maturation due to associated conditions including celiac disease, inflammatory bowel diseases, kidney insufficiency, and anorexia nervosa. Permanent hypogonadotropic hypogonadism (pHH) showing low serum value of testosterone or estradiol and blunted follicle-stimulating hormones (FSH) and luteinizing hormones (LH) levels may be due to abnormalities in the central nervous system. Therefore, magnetic resonance imaging is necessary to exclude morphological abnormalities and neoplasia. Moreover, pHH may be isolated, as observed in Kallmann syndrome, or associated with other hormone deficiencies, as found in panhypopituitarism. Baseline or gonadotropin-releasing hormone pituitary stimulated gonadotropin level is not sufficient to easily differentiate CDGP from pHH. Low serum testosterone in male patients and low estradiol values in female patients, associated with high serum FSH and LH levels, suggest a diagnosis of hypergonadotropic hypogonadism. A genetic analysis can reveal a chromosomal abnormality (e.g., Turner syndrome or Klinefelter syndrome). In cases where the adolescent with CDGP is experiencing psychological difficulties, treatment should be recommended.

RNA-seq analysis of lncRNA-controlled developmental gene expression during puberty in goat & rat

Background

Puberty is a pivotal stage in female animal development, and marks the onset of reproductive capability. However, little is known about the function of lncRNAs (long noncoding RNAs) in puberty. Therefore, RNA-seq analysis were performed between goats and rats to clarify the roles of lncRNAs and mRNAs in the onset of puberty.

Results

In the present study, the length of lncRNAs, the length of the open reading frame and the exon count were compared between the two species. Furthermore, functional annotation analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis of lncRNAs target genes and differentially expressed mRNA demonstrated the significantly enriched terms, such as AMPK signaling pathway, oxytocin signaling pathway, insulin secretion as well as pheromone receptor activity, and some other signaling pathways which were involved in the regulation of female puberty. Moreover, our results of siRNA interference in vitro showed the candidate lncRNA XLOC_446331 may play a crucial role in regulating female puberty.

Conclusion

In conclusion, the RNA-seq analysis between goat and rat provide novel candidate regulators for genetic and molecular studies on female puberty.

Electronic supplementary material

The online version of this article (10.1186/s12863-018-0608-9) contains supplementary material, which is available to authorized users.

Disentangling puberty: novel neuroendocrine pathways and mechanisms for the control of mammalian puberty

BACKGROUND

Puberty is a complex developmental event, controlled by sophisticated regulatory networks that integrate peripheral and internal cues and impinge at the brain centers driving the reproductive axis. The tempo of puberty is genetically determined but is also sensitive to numerous modifiers, from metabolic and sex steroid signals to environmental factors. Recent epidemiological evidence suggests that the onset of puberty is advancing in humans, through as yet unknown mechanisms. In fact, while much knowledge has been gleaned recently on the mechanisms responsible for the control of mammalian puberty, fundamental questions regarding the intimate molecular and neuroendocrine pathways responsible for the precise timing of puberty and its deviations remain unsolved.

OBJECTIVE AND RATIONALE

By combining data from suitable model species and humans, we aim to provide a comprehensive summary of our current understanding of the neuroendocrine mechanisms governing puberty, with particular focus on its central regulatory pathways, underlying molecular basis and mechanisms for metabolic control.

SEARCH METHODS

A comprehensive MEDLINE search of articles published mostly from 2003 to 2017 has been carried out. Data from cellular and animal models (including our own results) as well as clinical studies focusing on the pathophysiology of puberty in mammals were considered and cross-referenced with terms related with central neuroendocrine mechanisms, metabolic control and epigenetic/miRNA regulation.

OUTCOMES

Studies conducted during the last decade have revealed the essential role of novel central neuroendocrine pathways in the control of puberty, with a prominent role of kisspeptins in the precise regulation of the pubertal activation of GnRH neurosecretory activity. In addition, different transmitters, including neurokinin-B (NKB) and, possibly, melanocortins, have been shown to interplay with kisspeptins in tuning puberty onset. Alike, recent studies have documented the role of epigenetic mechanisms, involving mainly modulation of repressors that target kisspeptins and NKB pathways, as well as microRNAs and the related binding protein, Lin28B, in the central control of puberty. These novel pathways provide the molecular and neuroendocrine basis for the modulation of puberty by different endogenous and environmental cues, including nutritional and metabolic factors, such as leptin, ghrelin and insulin, which are known to play an important role in pubertal timing.

WIDER IMPLICATIONS

Despite recent advancements, our understanding of the basis of mammalian puberty remains incomplete. Complete elucidation of the novel neuropeptidergic and molecular mechanisms summarized in this review will not only expand our knowledge of the intimate mechanisms responsible for puberty onset in humans, but might also provide new tools and targets for better prevention and management of pubertal deviations in the clinical setting.

Gene expression profiling of puberty-associated genes reveals abundant tissue and sex-specific changes across postnatal development

The timing of human puberty is highly variable, sexually dimorphic, and associated with adverse health outcomes. Over 20 genes carrying rare mutations have been identified in known pubertal disorders, many of which encode critical components of the hypothalamic-pituitary-gonadal (HPG) axis. Recent genome-wide association studies (GWAS) have identified more than 100 candidate genes at loci associated with age at menarche or voice breaking in males. We know little about the spatial, temporal or postnatal expression patterns of the majority of these puberty-associated genes. Using a high-throughput and sensitive microfluidic quantitative PCR strategy, we profiled the gene expression patterns of the mouse orthologs of 178 puberty-associated genes in male and female mouse HPG axis tissues, the pineal gland, and the liver at five postnatal ages spanning the pubertal transition. The most dynamic gene expression changes were observed prior to puberty in all tissues. We detected known and novel tissue-enhanced gene expression patterns, with the hypothalamus expressing the largest number of the puberty-associated genes. Notably, over 40 puberty-associated genes in the pituitary gland showed sex-biased gene expression, most of which occurred peri-puberty. These sex-biased genes included the orthologs of candidate genes at GWAS loci that show sex-discordant effects on pubertal timing. Our findings provide new insight into the expression of puberty-associated genes and support the possibility that the pituitary plays a role in determining sex differences in the timing of puberty.

Association study of LIN28B in girls with precocious puberty

BACKGROUND

Central precocious puberty (CPP), predominant in girls, is defined by early development of secondary sexual characteristics driven by the early secretion of hypothalamic gonadotropin releasing hormone (GnRH) and subsequent gonadotropin. Recent studies have shown variation in the LIN28B gene is associated with timing of puberty, but only a few have show it to be associated with CPP.

METHODS

This study attempted to investigate the relation between single-nucleotide polymorphisms (SNPs) in LIN28B and girls with precocious puberty. Genotype and alleles frequencies of selected SNPs were compared between 116 girls with CPP and 102 controls.

RESULTS

We found genotype frequencies in rs314276 and rs221634 were significantly correlated with girls with CPP; while the C allele frequency in rs314276 showed the dominant trait. Standard deviation score (SDS) of weight and body mass index (BMI) were higher in CC homozygotes of rs314276 in girls with CPP.

CONCLUSIONS

Our results demonstrate that the genotype of rs314276 in LIN28B is associated with girls with CPP, carrying dominant trait in the C allele.

Preparation for sexual and reproductive self-care in Iranian adolescent girls: a qualitative study

Background Adolescence is one of the most important stages in every individual's life. Pubertal changes and acquiring reproduction capability require adolescents to perform special health care processes. Also the possibility of involvement in high-risk sexual behaviors endangers adolescent girls' sexual and reproductive health. Objective Increase and deepen the understanding and knowledge of the factors affecting Iranian adolescent girls' readiness to take care of their sexual and reproductive health. Materials and methods The present qualitative study was conducted using conventional content analysis method. The participants included 18 adolescents who were aged 13-19 years old, single, studying at high school, art school, or university and had no history of chronic medical or psychological diseases; further, most of them had the experience of menstruation. Purposive sampling was initiated and continued until data saturation. Data collection were performed using in-depth and unstructured interviews. Qualitative content analysis of the interviews was conducted simultaneously with data collection using the Graneheim and Lundman approach .MAXQDA 2010 software was used for storage, retrieval, and management of the data. Findings Preparation for care was the main theme that emerged in this study along with 19 subcategories and four main categories, including desirable interaction between families and adolescents, readiness for puberty and menstruation, life skills and spiritual self-monitoring. Conclusion The education and health care systems' authorities of the country can exploit the results of this study for making policies and interventions expedient to the society's cultural conditions in order to improve the reproductive and sexual self-care status of adolescents' girls.

Genetic Variations of the KISS1R Gene in Korean Girls with Central Precocious Puberty

The timing of puberty onset varies greatly among individuals, and much of this variation is modulated by genetic factors. This study aimed to identify the kisspeptin receptor (KISS1R) gene variations and to investigate the associations between these variations and central precocious puberty (CPP). Korean girls with CPP (n = 194) and their healthy controls (n = 99) were included in this study. The entire coding region and the exon-intron boundaries (exon 1 through 5) of the KISS1R gene were directly sequenced. Seven polymorphisms were identified in the KISS1R gene. A missense change c.1091T>A, and an intron variant c.738+64G>T showed significantly higher allele frequencies in CPP patients than in controls (c.1091T>A: 30.7% vs. 22.2%, P = 0.031; c.738+64G>T: 45.6% vs. 35.9%, P = 0.023). The missense variant (c.1091T>A) was a nonsynonymous polymorphism that induces amino acid substitution of p.Leu364His. The haplotype CAGTGTC was detected more frequently in the CPP group (P = 0.042). The sequence variants of the KISS1R gene can be inducible factors in the development of CPP. The association between sequence variants and CPP should be validated by further evidence obtained from larger samples of children with CPP.

Clinical Exome Sequencing Reveals MKRN3 Pathogenic Variants in Familial and Nonfamilial Idiopathic Central Precocious Puberty

BACKGROUND/AIMS

Idiopathic central precocious puberty (ICPP) is the premature activation of the hypothalamic-pituitary-gonadal axis in the absence of organic disease. Up to now, just gain-of-function mutations of KISS1/KISS1R and loss-of-function mutations of the maternally imprinted gene MKRN3 are the known genetic causes of ICPP. Our intention is to evaluate variants present in genes related to the pubertal onset pathway that could act as disease-causing or predisposing variants.

METHODS

We studied the clinical exome of 20 patients diagnosed with ICPP using the Illumina platform. The bioinformatics analysis was performed using 2 different programs, and the variants were filtered according to a list of genes related to the gonadotropin-releasing hormone pathway.

RESULTS

In a "sporadic case," we found a missense variant in MKRN3 NM_005664.3: c.203G>A, causing the protein change NP_005655.1:p.Arg68His, predicted as pathogenic by 2 informatics tools. The proband carrying this variant was diagnosed with ICPP at 7.75 years of age. We did not find any pathogenic variants in KISS1, KISS1R, LIN28, GNRH, GNRHR, TACR3, and TAC3.

CONCLUSION

MKRN3 is the most frequent genetic cause of familial ICPP, so it is wise to screen for MKRN3 mutations in all patients with familial ICPP and in patients with an unclear paternal pubertal history.

RASopathies Are Associated With Delayed Puberty; Are They Associated With Precocious Puberty Too?

RASopathies, such as Noonan, Costello, and cardio-facio-cutaneous syndromes, are developmental disorders caused by mutations in rat sarcoma-mitogen-activated protein kinase pathway genes. Mutations that cause Noonan syndrome have been associated with delayed puberty. Here we report 4 patients with either Costello or cardio-facio-cutaneous syndrome who developed precocious puberty, suggesting complex regulation of the hypothalamic-pituitary-gonadal axis and the timing of puberty by the rat sarcoma-mitogen-activated protein kinase pathway. Additional study of the timing of puberty among patients with RASopathies is warranted to ascertain the incidence of delayed and precocious puberty in these conditions and to examine genotype-phenotype correlations, which may provide insight into pathways that regulate the timing of puberty.

Determinants of puberty health among female adolescents residing in boarding welfare centers in Tehran: An application of health belief model

Background: Adolescence is a critical stage of growth and development. That is associated with changes in body shape and appearance. Issues such as irregular menstrual periods, amenorrhea, and menstrual cycle are major issues in women's health. The purpose of this study was to examine the determinants of physical puberty health based on the Health Belief Model (HBM) among female adolescents. Methods: This analytical cross sectional study was conducted in welfare boarding centers in Tehran, Iran. Data were collected in 2011 by a structured and valid questionnaire. Total 61 female adolescents (age range: 12-19 yrs) participated in this study from welfare boarding centers in Iran, Tehran, by using convenience sampling method. The questionnaire consisted of demographic characteristics, health belief model constructs and physical puberty health behaviors gathered by using interview. A series of univariate general linear models were used to assess the relationship between puberty health and health belief model constructs. Results: According to the results of this study there were positive significant relationships between perceived susceptibility, perceived benefits, perceived barriers, cues to action and increased puberty health in female adolescents (p<0.05). Perceived benefits, perceived barriers and cues to action were predictors of physical puberty health behaviors. Conclusion: Based on the results of the study to improve the physical Puberty health behaviors of female adolescents should make them aware of the benefits of health behaviors, and remove or reform the perceived barriers of health behaviors. Also, the appropriate information resources should be introduced for obtaining information about puberty health.

Metabolic control of female puberty: potential therapeutic targets

INTRODUCTION

The onset of puberty in females is highly sensitive to the nutritional status and the amount of energy reserves of the organism. This metabolic information is sensed and transmitted to hypothalamic GnRH neurons, considered to be ultimately responsible for triggering puberty through the coordinated action of different peripheral hormones, central neurotransmitters, and molecular mediators.

AREAS COVERED

This article will review and discuss (i) the relevant actions of the adipose hormone leptin, as a stimulatory/permissive signal, and the gut hormone ghrelin, as an inhibitory factor, in the metabolic control of female puberty; (ii) the crucial role of the hypothalamic kisspeptin neurons, recently emerged as essential gatekeepers of puberty, in transmitting this metabolic information to GnRH neurons; and (iii) the potential involvement of key cellular energy sensors, such as mTOR, as molecular mediators in this setting.

EXPERT OPINION

The thorough characterization of the physiological roles of the above elements in the metabolic control of female puberty, along with the discovery of novel factors, pathways, and mechanisms involved, will promote our understanding of the complex networks connecting metabolism and puberty and, ultimately, will aid in the design of target-specific treatments for female pubertal disorders linked to conditions of metabolic stress.

Pubertal development and regulation

Puberty marks the end of childhood and is a period when individuals undergo physiological and psychological changes to achieve sexual maturation and fertility. The hypothalamic-pituitary-gonadal axis controls puberty and reproduction and is tightly regulated by a complex network of excitatory and inhibitory factors. This axis is active in the embryonic and early postnatal stages of life and is subsequently restrained during childhood, and its reactivation culminates in puberty initiation. The mechanisms underlying this reactivation are not completely known. The age of puberty onset varies between individuals and the timing of puberty initiation is associated with several health outcomes in adult life. In this Series paper, we discuss pubertal markers, epidemiological trends of puberty initiation over time, and the mechanisms whereby genetic, metabolic, and other factors control secretion of gonadotropin-releasing hormone to determine initiation of puberty.

Makorin ortholog LEP-2 regulates LIN-28 stability to promote the juvenile-to-adult transition in Caenorhabditis elegans

The heterochronic genes lin-28, let-7 and lin-41 regulate fundamental developmental transitions in animals, such as stemness versus differentiation and juvenile versus adult states. We identify a new heterochronic gene, lep-2, in Caenorhabditis elegans. Mutations in lep-2 cause a delay in the juvenile-to-adult transition, with adult males retaining pointed, juvenile tail tips, and displaying defective sexual behaviors. In both sexes, lep-2 mutants fail to cease molting or produce an adult cuticle. We find that LEP-2 post-translationally regulates LIN-28 by promoting LIN-28 protein degradation. lep-2 encodes the sole C. elegans ortholog of the Makorin (Mkrn) family of proteins. Like lin-28 and other heterochronic pathway members, vertebrate Mkrns are involved in developmental switches, including the timing of pubertal onset in humans. Based on shared roles, conservation and the interaction between lep-2 and lin-28 shown here, we propose that Mkrns, together with other heterochronic genes, constitute an evolutionarily ancient conserved module regulating switches in development.

Targeted resequencing of the pericentromere of chromosome 2 linked to constitutional delay of growth and puberty

Constitutional delay of growth and puberty (CDGP) is the most common cause of pubertal delay. CDGP is defined as the proportion of the normal population who experience pubertal onset at least 2 SD later than the population mean, representing 2.3% of all adolescents. While adolescents with CDGP spontaneously enter puberty, they are at risk for short stature, decreased bone mineral density, and psychosocial problems. Genetic factors contribute heavily to the timing of puberty, but the vast majority of CDGP cases remain biologically unexplained, and there is no definitive test to distinguish CDGP from pathological absence of puberty during adolescence. Recently, we published a study identifying significant linkage between a locus at the pericentromeric region of chromosome 2 (chr 2) and CDGP in Finnish families. To investigate this region for causal variation, we sequenced chr 2 between the genomic coordinates of 79-124 Mb (genome build GRCh37) in the proband and affected parent of the 13 families contributing most to this linkage signal. One gene, DNAH6, harbored 6 protein-altering low-frequency variants (< 6% in the Finnish population) in 10 of the CDGP probands. We sequenced an additional 135 unrelated Finnish CDGP subjects and utilized the unique Sequencing Initiative Suomi (SISu) population reference exome set to show that while 5 of these variants were present in the CDGP set, they were also present in the Finnish population at similar frequencies. Additional variants in the targeted region could not be prioritized for follow-up, possibly due to gaps in sequencing coverage or lack of functional knowledge of non-genic genomic regions. Thus, despite having a well-characterized sample collection from a genetically homogeneous population with a large population-based reference sequence dataset, we were unable to pinpoint variation in the linked region predisposing delayed puberty. This study highlights the difficulties of detecting genetic variants under linkage regions for complex traits and suggests that advancements in annotation of gene function and regulatory regions of the genome will be critical for solving the genetic background of complex phenotypes like CDGP.

Mutations in KISS1 are not responsible for idiopathic hypogonadotropic hypogonadism in Chinese patients

PURPOSE

To investigate whether mutations in the KISS1 gene are present in 170 Chinese patients with idiopathic hypogonadotropic hypogonadism (IHH).

METHODS

Mutational screening of the KISS1 gene was performed in 170 Chinese patients with IHH (133 male cases and 37 female cases) and 187 matched controls (94 males and 93 females).

RESULTS

Two known single-nucleotide polymorphisms (SNP), c. 58G > A in exon 1 and c. 242C > G in exon 2, were identified. However, no difference of genotype and allelic frequencies between cases and controls was observed.

CONCLUSIONS

The results suggest that mutations in the coding sequence of KISS1 are not common in patients with IHH in this Chinese population.

Associations between menarche-related genetic variants and pubertal growth in male and female adolescents

PURPOSE

Previous studies have identified novel genetic variants associated with age at menarche in females of European descent. The pubertal growth effects of these variants have not been carefully evaluated in non-European descent groups. We aimed to examine the effects of 31 newly identified menarche-related single-nucleotide polymorphisms (SNPs) on growth outcomes in African-American (AA) and European-American (EA) children in a prospective cohort.

METHODS

We analyzed longitudinal data collected from 263 AAs and 338 EAs enrolled between ages 5 and 17 years; the subjects were followed semiannually for an average of 6 years. The associations between the SNPs and growth-related outcomes, including weight, height, and body mass index (BMI), were examined using mixed-effect models.

RESULTS

Longitudinal analyses revealed that 4 (near or in genes VGLL3, PEX2, CA10, and SKOR2) of the 14 menarche-only-related SNPs were associated with changes in weight and BMI in EA and AA (p ≤ .0032), but none of them was associated with changes in height. Of the eight menarche-timing and BMI-related SNPs, none was associated with changes in height, but three (in or near genes NEGR1, ETV5, and FTO) were associated with more rapid increases in weight and/or BMI in EA (p ≤ .0059). Among the nine menarche-timing and height-related SNPs, four (in or near genes ZBTB38, LOC728666, TBX2, and CABLES) were associated with changes in weight or height in EA and AA (p ≤ .0042).

CONCLUSIONS

Genetic variants related to age at menarche were found to be associated with various growth parameters in healthy adolescents. The identified associations were often race and sex specific.

Associations between menarche-related genetic variants and pubertal growth in male and female adolescents

PURPOSE

Previous studies have identified novel genetic variants associated with age at menarche in females of European descent. The pubertal growth effects of these variants have not been carefully evaluated in non-European descent groups. We aimed to examine the effects of 31 newly identified menarche-related single-nucleotide polymorphisms (SNPs) on growth outcomes in African-American (AA) and European-American (EA) children in a prospective cohort.

METHODS

We analyzed longitudinal data collected from 263 AAs and 338 EAs enrolled between ages 5 and 17 years; the subjects were followed semiannually for an average of 6 years. The associations between the SNPs and growth-related outcomes, including weight, height, and body mass index (BMI), were examined using mixed-effect models.

RESULTS

Longitudinal analyses revealed that 4 (near or in genes VGLL3, PEX2, CA10, and SKOR2) of the 14 menarche-only-related SNPs were associated with changes in weight and BMI in EA and AA (p ≤ .0032), but none of them was associated with changes in height. Of the eight menarche-timing and BMI-related SNPs, none was associated with changes in height, but three (in or near genes NEGR1, ETV5, and FTO) were associated with more rapid increases in weight and/or BMI in EA (p ≤ .0059). Among the nine menarche-timing and height-related SNPs, four (in or near genes ZBTB38, LOC728666, TBX2, and CABLES) were associated with changes in weight or height in EA and AA (p ≤ .0042).

CONCLUSIONS

Genetic variants related to age at menarche were found to be associated with various growth parameters in healthy adolescents. The identified associations were often race and sex specific.

Pubertal timing, bone acquisition, and risk of fracture throughout life

Pubertal maturation plays a fundamental role in bone acquisition. In retrospective epidemiological surveys in pre- and postmenopausal women, relatively later menarcheal age was associated with low bone mineral mass and increased risk of osteoporotic fracture. This association was usually ascribed to shorter time exposure to estrogen from the onset of pubertal maturation to peak bone mass attainment. Recent prospective studies in healthy children and adolescents do not corroborate the limited estrogen exposure hypothesis. In prepubertal girls who will experience later menarche, a reduced bone mineral density was observed before the onset of pubertal maturation, with no further accumulated deficit until peak bone mass attainment. In young adulthood, later menarche is associated with impaired microstructural bone components and reduced mechanical resistance. This intrinsic bone deficit can explain the fact that later menarche increases fracture risk during childhood and adolescence. In healthy individuals, both pubertal timing and bone development share several similar characteristics including wide physiological variability and strong effect of heritable factors but moderate influence of environmental determinants such as nutrition and physical activity. Several conditions modify pubertal timing and bone acquisition, a certain number of them acting in concert on both traits. Taken together, these facts should prompt the search for common genetic regulators of pubertal timing and bone acquisition. It should also open epigenetic investigation avenues to pinpoint which environmental exposure in fetal and infancy life, such as vitamin D, calcium, and/or protein supplies, influences both pubertal timing and bone acquisition.

Role of gonadotropin-releasing hormone receptor mutations in patients with a wide spectrum of pubertal delay

OBJECTIVE

To analyze the GNRHR in patients with normosmic isolated hypogonadotropic hypogonadism (IHH) and constitutional delay of growth and puberty (CDGP).

DESIGN

Molecular analysis and in vitro experiments correlated with phenotype.

SETTING

Academic medical center.

PATIENT(S)

A total of 110 individuals with normosmic IHH (74 male patients) and 50 with CDGP.

INTERVENTION(S)

GNRHR coding region was amplified and sequenced.

MAIN OUTCOME MEASURE(S)

Novel variants were submitted to in vitro analysis. Frequency of mutations and genotype-phenotype correlation were analyzed. Microsatellite markers flanking GNRHR were examined in patients carrying the same mutation to investigate a possible founder effect.

RESULT(S)

Eleven IHH patients (10%) carried biallelic GNRHR mutations. In vitro analysis of novel variants (p.Y283H and p.V134G) demonstrated complete inactivation. The founder effect study revealed that Brazilian patients carrying the p.R139H mutation shared the same haplotype. Phenotypic spectrum in patients with GNRHR mutations varied from complete GnRH deficiency to partial and reversible IHH, with a relatively good genotype-phenotype correlation. One boy with CDGP was heterozygous for the p.Q106R variant, which was not considered to be pathogenic.

CONCLUSION(S)

GNRHR mutations are a frequent cause of congenital normosmic IHH and should be the first candidate gene for genetic screening in this condition, especially in autosomal recessive familial cases. The founder effect study suggested that the p.R139H mutation arises from a common ancestor in the Brazilian population. Finally, mutations in GNRHR do not appear to be involved in the pathogenesis of CDGP.

Factors influencing menarcheal age: results from the cohort of tehran lipid and glucose study

BACKGROUND

Menarche is considered as a milestone in the women's reproductive life. Most existing studies on factors influencing menarcheal age had cross-sectional designs and their finding were controversial.

OBJECTIVES

We aimed to determine some factors affecting the age at menarche in a cohort study with an average of ten-year follow-up; the study was conducted within the framework of Tehran Lipid and Glucose Study (TLGS).

MATERIALS AND METHODS

For the purpose of the present study, we recruited all the females aged 12 to 18 years participated in TLGS whose menarche had not begun at the initiation of the study, but occurred during their follow-up. The effect of premenarcheal status of various factors including socioeconomic and anthropometric parameters, physical activity, energy expenditure, and exposure to tobacco smoke on menarcheal age was explored.

RESULTS

The mean of age at menarche was 13.06 ± 1.24 years. There were significant statistical associations between age of the participants' mothers at menarche (r = 0.66, P < 0.001), maternal education (r = -0.04, P = 0.002), and body mass index (BMI) before menarcheal (r = 0.25, P = 0.027) with age at menarche. There was no significant correlation between age at menarche, with either of maternal employment, premenarcheal physical activity, energy expenditure, and passive smoking.

CONCLUSIONS

Among various factor influencing menarcheal age, premenarcheal BMI is modifiable, and considering its significance, could prevent early or late menarches.

Growth and body composition in Brazilian female rhythmic gymnastics athletes

The aim was to analyse the physical growth and body composition of rhythmic gymnastics athletes relative to their level of somatic maturation. This was a cross-sectional study of 136 athletes on 23 teams from Brazil. Mass, standing height and sitting height were measured. Fat-free and fat masses, body fat percentages and ages of the predicted peak height velocity (PHV) were calculated. The z scores for mass were negative during all ages according to both WHO and Brazilian references, and that for standing height were also negative for all ages according to WHO reference but only until 12 years old according to Brazilian reference. The mean age of the predicted PHV was 12.1 years. The mean mass, standing and sitting heights, body fat percentage, fat-free mass and fat mass increased significantly until 4 to 5 years after the age of the PHV. Menarche was reached in only 26% of these athletes and mean age was 13.2 years. The mass was below the national reference standards, and the standing height was below only for the international reference, but they also had late recovery of mass and standing height during puberty. In conclusion, these athletes had a potential to gain mass and standing height several years after PHV, indicating late maturation.