Arch. Endocrinol. Metab. 2015;59(2):93-94
Puberty: When is it normal?
DOI: 10.1590/2359-3997000000018
Classically, the normal chronological age for pubertal onset is between 8 and 13 years in girls and 9 and 14 years in boys based on data from epidemiological studies from the 60’s (). However, the age limit for pubertal timing is still a challenge (,). It is well known that puberty is a complex and multi factorial process that involves genetic, metabolic, socio economic, nutritional and ethnic factors. Moreover, the evidence that initial pubertal signs, mainly in girls, are appearing earlier today than in the last 4 decades has been described by several epidemiological studies (-).
In the last years, genetic control of pubertal onset has been demonstrated through the identification of pathogenic mutations. Several loss-of-function mutations of MKRN3, a gene encoding the makorin RING-finger protein 3, result in familial central precocious puberty, suggesting a potential inhibitory input to gonadotropin-releasing hormone (GnRH) secretion (). Interestingly, the mean age of pubertal onset in MKRN3 affected girls was 6.0 years (ranging from 3.0 yr to 7.0). Notably, pubertal timing, pubertal height growth and age at menarche are strongly associated with adiposity in both epidemiological and genetic studies, since genome-wide association studies revealed genetic loci linking pubertal height growth, pubertal timing and childhood adiposity (). The relationship between pubertal timing and adiposity is stronger in girls. Environmental factors, such as endocrine chemical disruptors (pesticides, phthalates, bisphenol A, and plant-derived phytoestrogens) or low levels of estrogens in the food supply have been influenced the timing of puberty, leading to precocity or delay in this process, specially, in animal models ().
[…]