Repeated assessment by high-throughput assay demonstrates that sperm DNA methylation levels are highly reproducible.
OBJECTIVE
To assess reliability of a high-throughput assay of sperm DNA methylation.


METHODS
Observational study comparing DNA methylation of sperm isolated from 3 divided and 12 longitudinally collected semen samples.


METHODS
Academic medical center.


METHODS
One man undergoing screening semen analysis during evaluation of an infertile couple and 2 healthy fertile male volunteers.


METHODS
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.


METHODS
Repeatability of sperm DNA methylation measures, estimated by correlation coefficients.


RESULTS
DNA methylation levels were highly correlated within matched sets of divided samples (all r ≥ 0.97) and longitudinal samples (average r = 0.97).


CONCLUSIONS
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.
Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA. cortessi@usc.edu
Victoria K
VK
Cortessis
Kimberly
K
Siegmund
Sahar
S
Houshdaran
Peter W
PW
Laird
Rebecca Z
RZ
Sokol
D019175:DNA Methylation / Q000502:physiology; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D007248:Infertility, Male / Q000235:genetics / Q000378:metabolism; D008137:Longitudinal Studies; D008297:Male; D015203:Reproducibility of Results; D055101:Semen Analysis; D012680:Sensitivity and Specificity; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*; D013997:Time Factors; D054928:Validation Studies as Topic