Abstract
OBJECTIVE: To assess reliability of a high-throughput assay of sperm DNA methylation. DESIGN: Observational study comparing DNA methylation of sperm isolated from 3 divided and 12 longitudinally collected semen samples. SETTING: Academic medical center. PATIENT(S): One man undergoing screening semen analysis during evaluation of an infertile couple and 2 healthy fertile male volunteers. INTERVENTION(S): Spermatozoa were separated from seminal plasma and somatic cells using gradient separation. DNA was extracted from spermatozoa, and DNA methylation was assessed at 1,505 DNA sequence-specific sites. MAIN OUTCOME MEASURE(S): Repeatability of sperm DNA methylation measures, estimated by correlation coefficients. RESULT(S): DNA methylation levels were highly correlated within matched sets of divided samples (all r ≥ 0.97) and longitudinal samples (average r = 0.97). CONCLUSION(S): The described methodology reliably assessed methylation of sperm DNA at large numbers of sites. Methylation profiles were consistent over time. High-throughput assessment of sperm DNA methylation is a promising tool for studying the role of epigenetic state in male fertility.