Repeated assessment by high-throughput assay demonstrates that sperm DNA methylation levels are highly reproducible

<bold>Objective: </bold>To assess reliability of a high-throughput assay of sperm DNA methylation.<bold>Design: </bold>Observational study comparing DNA methylation of sperm isolated from 3 divided and 12 longitudinally collected semen samples.<bold>Setting: </bold>Academic medical center.<bold>Patient(s): </bold>One man undergoing screening semen analysis during evaluation of an infertile couple and 2 healthy fertile male volunteers.<bold>Intervention(s): </bold>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.<bold>Main Outcome Measure(s): </bold>Repeatability of sperm DNA methylation measures, estimated by correlation coefficients.<bold>Result(s): </bold>DNA methylation levels were highly correlated within matched sets of divided samples (all r ≥ 0.97) and longitudinal samples (average r = 0.97).<bold>Conclusion(s): </bold>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. [ABSTRACT FROM AUTHOR]