Leukocyte telomere length and DNA methylome as biomarkers of ovarian reserve and embryo aneuploidy: The intricate relationship between somatic and reproductive aging.

The average childbearing age amongst women continues to rise, leading to an increased prevalence of infertility and a subsequent increased use of assisted reproductive technologies (ART). Ovarian aging, especially diminished ovarian reserve (DOR) and poor ovarian response (POR) have been implicated as common causes of infertility. Telomere length and DNA methylation-based epigenetic clocks are established hallmarks of cellular aging, however, the interplay between somatic and ovarian aging remains unclear. There appears to be a lack of correlation between leukocyte telomere length and DNA methylation age of somatic and ovarian cells. Both the telomere length and methylome of follicular somatic cells (granulosa and cumulus) appear to be unaffected by chronologic age, infertility, or processes that result in DOR/POR. As such they are unlikely candidates as surrogate biomarkers of reproductive potential, response to stimulation, or ART outcome. On the other hand, telomere or methylome changes in leukocytes associated with aging seem to correlate with reproductive function and may have the potential to aid the characterization of women with reproductive decline, however, current data is limited and larger studies evaluating this within an ART setting are warranted.