Puberty is the period during which we attain adult secondary sexual characteristics and reproductive capability. Its onset depends upon reactivation of pulsative GNRH, secretion from its relative quiescence during childhood, on the background of intact potential for pituitary–gonadal function. This review is intended: to highlight those current practices in diagnosis and management that are evidence based and those that are not; to help clinicians deal with areas of uncertainty with reference to physiologic first principles; by sign-posting relevant data arising from other patient groups with shared issues; to illustrate how recent scientific advances are (or should be) altering clinician perceptions of pubertal delay; and finally, to emphasise that the management of men and women presenting in advanced adult life with absent puberty cannot simply be extrapolated from paediatric practice. There is a broad spectrum of pubertal timing that varies among different populations, separated in time and space. Delayed puberty usually represents an extreme of the normal, a developmental pattern referred to as constitutional delay of growth and puberty (CDGP), but organic defects of the hypothalamo–pituitary–gonadal axis predisposing to hypogonadism may not always be initially distinguishable from it. CDGP and organic, or congenital hypogonadotrophic hypogonadism are both significantly more common in boys than girls. Moreover, around 1/3 of adults with organic hypogonadotrophic hypogonadism had evidence of partial puberty at presentation and, confusingly, some 5–10% of these subsequently may exhibit recovery of endogenous gonadotrophin secretion, including men with Kallmann syndrome. However, the distinction is crucial as expectative (‘watch-and-wait’) management is inappropriate in the context of hypogonadism. The probability of pubertal delay being caused by organic hypogonadism rises exponentially both with increasing age at presentation and the presence of associated ‘red flag’ clinical features. These ‘red flags’ comprise findings indicating lack of prior ‘mini-puberty’ (such as cryptorchidism or micropenis), or the presence of non-reproductive congenital defects known to be associated with specific hypogonadal syndromes, e.g. anosmia, deafness, mirror movements, renal agenesis, dental/digital anomalies, clefting or coloboma would be compatible with Kallmann (or perhaps CHARGE) syndrome. In children, interventions (whether in the form or treatment or simple reassurance) have been historically directed at maximising height potential and minimising psychosocial morbidity, though issues of future fertility and bone density potential are now increasingly ‘in the mix’. Apubertal adults almost invariably harbour organic hypogonadism, requiring sensitive acknowledgement of underlying personal issues and the timely introduction of sex hormone replacement therapy at more physiological doses.
Leo Dunkel and Richard Quinton
Roberto Salvatori, Serban Radian, Yoan Diekmann, Donato Iacovazzo, Alessia David, Plamena Gabrovska, Giorgia Grassi, Anna-Marie Bussell, Karen Stals, Astrid Weber, Richard Quinton, Elizabeth C Crowne, Valentina Corazzini, Lou Metherell, Tara Kearney, Daniel Du Plessis, Ajay Kumar Sinha, Atik Baborie, Anne-Lise Lecoq, Philippe Chanson, Olaf Ansorge, Sian Ellard, Peter J Trainer, David Balding, Mark G Thomas and Márta Korbonits
Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are associated with pituitary adenoma, acromegaly and gigantism. Identical alleles in unrelated pedigrees could be inherited from a common ancestor or result from recurrent mutation events.
Design and methods
Observational, inferential and experimental study, including: AIP mutation testing; reconstruction of 14 AIP-region (8.3 Mbp) haplotypes; coalescent-based approximate Bayesian estimation of the time to most recent common ancestor (tMRCA) of the derived allele; forward population simulations to estimate current number of allele carriers; proposal of mutation mechanism; protein structure predictions; co-immunoprecipitation and cycloheximide chase experiments.
Nine European-origin, unrelated c.805_825dup-positive pedigrees (four familial, five sporadic from the UK, USA and France) included 16 affected (nine gigantism/four acromegaly/two non-functioning pituitary adenoma patients and one prospectively diagnosed acromegaly patient) and nine unaffected carriers. All pedigrees shared a 2.79 Mbp haploblock around AIP with additional haploblocks privately shared between subsets of the pedigrees, indicating the existence of an evolutionarily recent common ancestor, the ‘English founder’, with an estimated median tMRCA of 47 generations (corresponding to 1175 years) with a confidence interval (9–113 generations, equivalent to 225–2825 years). The mutation occurred in a small tandem repeat region predisposed to slipped strand mispairing. The resulting seven amino-acid duplication disrupts interaction with HSP90 and leads to a marked reduction in protein stability.
The c.805_825dup allele, originating from a common ancestor, associates with a severe clinical phenotype and a high frequency of gigantism. The mutation is likely to be the result of slipped strand mispairing and affects protein–protein interactions and AIP protein stability.
Daniele Cassatella, Sasha R Howard, James S Acierno, Cheng Xu, Georgios E Papadakis, Federico A Santoni, Andrew A Dwyer, Sara Santini, Gerasimos P Sykiotis, Caroline Chambion, Jenny Meylan, Laura Marino, Lucie Favre, Jiankang Li, Xuanzhu Liu, Jianguo Zhang, Pierre-Marc Bouloux, Christian De Geyter, Anne De Paepe, Waljit S Dhillo, Jean-Marc Ferrara, Michael Hauschild, Mariarosaria Lang-Muritano, Johannes R Lemke, Christa Flück, Attila Nemeth, Franziska Phan-Hug, Duarte Pignatelli, Vera Popovic, Sandra Pekic, Richard Quinton, Gabor Szinnai, Dagmar l’Allemand, Daniel Konrad, Saba Sharif, Özlem Turhan Iyidir, Brian J Stevenson, Huanming Yang, Leo Dunkel and Nelly Pitteloud
Congenital hypogonadotropic hypogonadism (CHH) and constitutional delay of growth and puberty (CDGP) represent rare and common forms of GnRH deficiency, respectively. Both CDGP and CHH present with delayed puberty, and the distinction between these two entities during early adolescence is challenging. More than 30 genes have been implicated in CHH, while the genetic basis of CDGP is poorly understood.
We characterized and compared the genetic architectures of CHH and CDGP, to test the hypothesis of a shared genetic basis between these disorders.
Exome sequencing data were used to identify rare variants in known genes in CHH (n = 116), CDGP (n = 72) and control cohorts (n = 36 874 ExAC and n = 405 CoLaus).
Mutations in at least one CHH gene were found in 51% of CHH probands, which is significantly higher than in CDGP (7%, P = 7.6 × 10−11) or controls (18%, P = 5.5 × 10−12). Similarly, oligogenicity (defined as mutations in more than one gene) was common in CHH patients (15%) relative to CDGP (1.4%, P = 0.002) and controls (2%, P = 6.4 × 10−7).
Our data suggest that CDGP and CHH have distinct genetic profiles, and this finding may facilitate the differential diagnosis in patients presenting with delayed puberty.