Methylation status of the SNRPN and HUMARA genes in testicular biopsy samples

Abstract

To analyze the methylation status of two differentially inherited and methylated loci (the human androgen receptor [HUMARA] and the small nuclear ribonucleoprotein-associated polypeptide N [SNRPN] gene) in testicular biopsy samples, and to compare the results with microscopic evaluation. Retrospective study. Infertility clinics and genetics laboratories. Twelve obstructive and 74 nonobstructive azoospermic men. Deoxyribonucleic acid samples from testicular biopsies and peripheral blood were modified with sodium bisulfite and amplified by methylation-specific polymerase chain reaction assay. Polymerase chain reaction primers specific for the methylated regions of the HUMARA locus and for the methylated and unmethylated CpG islands of the SNRPN gene were used. Polymerase chain reaction product bands specific for methylated and unmethylated alleles. Obstructive azoospermia patients were positive for spermatozoa and germ cells by all approaches (microscopic, HUMARA, and SNRPN analysis) with absolute consistency. In contrast, for the nonobstructive men, microscopy was consistent with SNRPN analysis as regards the presence of germ cells in 82% of the testicular tissues tested. Nonobstructive patients with maturation arrest were positive for the presence of germ cells only by HUMARA analysis, with 84% sensitivity. Methylation analysis of testicular tissue is consistent with microscopic analysis, in terms of the prevalence of germ cells and the stage of spermatogenic arrest in biopsy samples.