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Abstract Background There are significant sex differences in human physiology and disease; the genomic sources of these differences, however, are not well understood. During puberty, a drastic neuroendocrine shift signals physical changes resulting in robust sex differences in human physiology. Here, we explore how shifting patterns of DNA methylation may inform these pathways of biological plasticity during the pubertal transition. In this study we analyzed DNA methylation (DNAm) in saliva at two time points across the pubertal transition within the same individuals. Our purpose was to compare two domains of DNAm patterns that may inform processes of sexual differentiation 1) sex related sites, which demonstrated differences between males from females and 2) time related sites in which DNAm shifted significantly between timepoints. We further explored the correlated network structure sex and time related DNAm networks and linked these patterns to pubertal stage, assays of salivary testosterone, a reliable diagnostic of free, unbound hormone that is available to act on target tissues, and overlap with androgen response elements. Results Sites that differed by biological sex were largely independent of sites that underwent change across puberty. Time-related DNAm sites, but not sex-related sites, formed correlated networks that were associated with pubertal stage. Both time and sex DNAm networks reflected salivary testosterone levels that were enriched for androgen response elements, with sex-related DNAm networks being informative of testosterone levels above and beyond biological sex later in the pubertal transition. Conclusions These results inform our understanding of the distinction between sex- and time-related differences in DNAm during the critical period of puberty and highlight a novel linkage between correlated patterns of sex-related DNAm and levels of salivary testosterone.

Background: The Alberta Immunization Program offers a vaccine against the Human Papillomavirus (HPV) free of charge to all girls in Grades 5 and 9. The vaccine is provided in two different service delivery models depending upon the acceptance of the program by the local school board. Vaccinations may be provided “in-school” or in “community” through appointments at Public Health Clinics. The purpose of this study was to determine whether there was a difference in vaccine uptake in Calgary between the two service delivery models, “in-school” and “community”, and to examine if socioeconomic status (SES) was a contributing factor. Methods: Individual data from the Calgary Zone Public Health vaccination database for all grade 5 and 9 girls in Calgary for school years 2008–2011 were analyzed using descriptive statistics. These data included vaccination records for 35,592 girls. Logistic regression was used to examine the effect of delivery system and SES status on being vaccinated, controlling for school type. Results: HPV vaccination completion rates were 75% (95% confidence interval = 74.7%, 75.8%) for girls with an “inschool” compared to 36% (95% confidence interval = 35.3%, 37.2%) for girls in schools with a “community” service delivery model. A girl’s neighbourhood SES was related to the likelihood of being HPV vaccinated depending on the service delivery model available to her. For girls attending a Public school with an “in-school” delivery model, the proportion completing vaccination increased as SES decreased (high SES = 79%; medium SES = 79%; low SES = 83%; p-value<0.001). For girls attending Calgary Catholic School District schools with the “community” delivery model there was a decrease in immunization rates from high and mid to low SES (high SES = 41%; medium SES = 42%; low SES = 34%; p-value<0.001). These results show that those with lower SES were differentially disadvantaged by not having access to an “in-school” vaccination delivery model. Conclusion: Service delivery models make a difference in HPV vaccination completion rates and create inequities for health protection and disease prevention based on socioeconomic status. [ABSTRACT FROM AUTHOR]