Methylation changes in mature sperm deoxyribonucleic acid from oligozoospermic men: assessment of genetic variants and assisted reproductive technology outcome.

OBJECTIVE

To characterize a potential genetic cause for methylation errors described in oligozoospermia.

DESIGN

Analysis of PEG1/MEST-DMR and H19-DMR methylation level in sperm, in parallel with the study of several genes on the Y chromosome, DNMT3A, and DNMT3L. Clinical outcome was also looked at regarding PEG1/MEST-DMR and H19-DMR methylation level in sperm.

SETTING

Research and diagnostic laboratories.

PATIENT(S): One hundred nineteen normospermic and 175 oligozoospermic men consulting for couple infertility.

INTERVENTION(S): We studied PEG1/MEST-DMR and H19-DMR methylation profiles in 294 men. We searched for Y chromosome gene aberrations and for mutations in both DNMT3A and DNMT3L genes in men showing epimutations. Assisted reproductive technology (ART) outcomes were also investigated.

MAIN OUTCOME MEASURE(S): Sperm samples were collected from 294 volunteers for genomic DNA isolation that was used to study methylation profiles in imprinted loci and Y chromosome SMCY, DNMT3A, and DNMT3L genes. Pregnancy rate was also studied after ART treatment using sperm showing epimutations.

RESULT(S): Epimutations in H19-DMR and PEG1/MEST-DMR were found in 20% and 3% of oligozoospermic men, respectively. We identified an amino acid change in DNMT3A in one case and in DNMT3L in eight men with altered methylation profiles. No mutations were detected in SMCY or in selected Y chromsome genes. No correlation between ART outcome and epimutations was found.

CONCLUSION(S): We observed epimethylations in spermatozoa of oligozoospermic individuals, but no association was found with genetic variants or in the ART outcome.