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Environmental and genetic contributors to salivary testosterone levels in infants

Kai Xia1, Yang Yu2, Mihye Ahn3

  • 1Department of Psychiatry, University of North Carolina at Chapel Hill , Chapel Hill, NC , USA.

Frontiers in Endocrinology
|November 18, 2014
PubMed

Insights

Infant testosterone levels, crucial for development, are mainly influenced by environmental factors, not genetics. Early life APGAR scores correlate with male infant testosterone.

Area of Science:

  • Endocrinology
  • Developmental Biology
  • Genetics

Background:

  • The hypothalamic-pituitary-gonadal axis is transiently activated in early infancy, influencing male genital development and brain sexual differentiation.
  • Factors affecting individual variations in infant testosterone levels remain poorly understood.

Purpose of the Study:

  • To investigate factors contributing to inter-individual variation in salivary testosterone levels in infants.
  • To estimate genetic and environmental contributions to testosterone levels using twin modeling.
  • To identify genetic variants associated with infant testosterone levels.

Main Methods:

  • Salivary testosterone levels were measured in 222 infants (2.70–4.80 months).
  • Demographic and medical history variables were analyzed.
  • Twin modeling was used to assess genetic and environmental influences.
  • Single nucleotide polymorphisms (SNPs) in genes related to testosterone pathways were tested for association.

Main Results:

  • An association was found between 5-minute APGAR scores and salivary testosterone in males.
  • Twin modeling indicated environmental factors primarily explain variability in testosterone levels.
  • Univariate genetic analysis showed no significant associations after false discovery rate adjustment.
  • Random forest analysis suggested genes involved in reproductive function (LHCGR) and cholesterol metabolism are related to male infant testosterone, while estrogen signaling genes relate to female infant testosterone.

Conclusions:

  • Environmental factors play a larger role than genetics in infant testosterone variability.
  • Specific genes and pathways are associated with testosterone levels in male and female infants.
  • Further research is needed to elucidate the genetic underpinnings of infant testosterone regulation.

Keywords:
APGARLHCGRhypothalamic–pituitary–gonadal axisinfancyminipubertyneonatetestosteronetwins

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