Alexander S Busch, Casper P Hagen, and Anders Juul
Pubertal timing is highly heritable. Observational studies were inconclusive concerning a potential sex-specific difference in the parental contribution, while genome-wide association studies highlighted a heterogeneity in the genetic architecture of pubertal timing between sexes. Our objectives were to evaluate the association of timing of pubertal milestones in offspring with parental pubertal timing and to identify the genetic basis of the heterogeneity.
(1.) Population-based mixed cross-sectional/longitudinal cohort (2006–2014, COPENHAGEN Puberty Study) comprising 1381 healthy Danish children including their parents. (2.) UK Biobank-based summary statistics of genetic data on timing of menarche (n = 188 644), voice-break (n = 154 459) and facial hair (n = 161 470).
(1.) Participants underwent clinical examination(s) including blood sampling. Parental pubertal timing was obtained by questionnaire. Timing of milestones were analyzed using SAS-lifereg. (2.) Genetic correlations between pubertal outcomes were estimated using LD Score regression. Genetic heterogeneity was analyzed using METAL.
We observed significant associations of relative parental pubertal timing with timing of pubertal milestones in offspring of concordant sex, that is, fathers/sons (e.g. testicular enlargement: P = 0.004, β = 0.34 years per relative category) and mothers/daughters (e.g. thelarche: P < 0.001, β = 0.45 years per relative category). Fewer milestones were associated with relative parental pubertal timing in offspring of discordant sex compared to concordant sex. Large-scale genetic data highlight both moderate to strong genetic correlations between timing of menarche, voice-break and facial hair. Out of 434 lead single-nucleotide polymorphisms significantly associated with at least one outcome, 39 exhibited a significant genetic heterogeneity between sexes (P < 1.15 × 10−4).
Our results highlight a distinct genetic heterogeneity of pubertal timing between sexes.
Mikkel G Mieritz, Kaspar Sorensen, Lise Aksglaede, Annette Mouritsen, Casper P Hagen, Linda Hilsted, Anna-Maria Andersson, and Anders Juul
Pubertal gynaecomastia is a frequent phenomenon occurring in 20–40% of otherwise healthy adolescent boys. Little is known about the aetiology of pubertal gynaecomastia. Markedly elevated thyroid hormone levels in adults with hyperthyroidism are associated with gynaecomastia.
A cross-sectional examination of 444 healthy boys with and without pubertal gynaecomastia.
We evaluated TSH, triiodothyronine (T3), thyroxine (T4), free T4 and free T3 in a cohort of healthy boys with and without pubertal gynaecomastia.
Boys with gynaecomastia had significantly higher serum free T3, even after correction for age, BMI and pubertal stage. After inclusion of IGF1 in the model the differences disappeared. TSH, T4, free T4 and T3 did not differ between the groups.
We speculate that the GH/IGF1 axis and thyroid hormones interact and influence the development of pubertal gynaecomastia.
Annette Mouritsen, Lise Aksglaede, Kaspar Soerensen, Casper P Hagen, J H Petersen, Katharina M Main, and Anders Juul
Pubertal onset is usually defined by breast development in girls and testicular growth in boys. Pubarche is defined as the attainment of pubic hair and is considered as a sign of pubertal transition. Pubarche is preceded by a gradual increase in production of adrenal androgens, DHEA and Δ4-androstenedione (Adione), a process termed adrenarche.
To study the natural course of pubertal transition and the associations with adrenarche, body fat, and linear growth.
Design and methods
A longitudinal study of 179 healthy children (89 girls) with higher socioeconomic background examined every 6 months for 5 years. Pubic hair stage, breast stage, genital stage, testicular volume (TV), height, weight, and four skinfolds were measured.
In girls, median age (25th and 75th percentiles) at thelarche (B2+) was 10.1 years (9.3–10.9). In boys, median age at attaining a TV >3 ml was 11.5 years (10.9–12.0). Median age at pubarche (PH2+) was 10.9 years (10.3–11.4) in girls and 11.6 years (10.8–12.4) in boys. Only 6.8% (4/59) of the girls and 24.6% (15/61) of the boys developed pubic hair as the first isolated sign of puberty. Serum DHEAS and Adione increased with age, although the increase in Adione was most pronounced in girls. No associations between early age at thelarche/testicular growth and increased body fat (BMI and sum of four skinfolds) were observed.
Danish children rarely experience pubarche as the first sign of puberty. No associations between age at pubertal onset and body composition were found. Circulating levels of Adione, but not DHEAS, increased with the onset of puberty, although with large interindividual variability.