Methylation of the SNRPN gene in infertile men without mutations in common candidate genes for reduced fertility

Abstract

Introduction. Male infertility is a common problem in andrology and occurs in 45 % of infertile couples. Some cases of male infertility caused by genetic reasons: point mutations at some monogenic diseases, AZF deletions or a CFTR mutation compounds; reduced fertility is also associated with polymorphic variants of the genes AR and GSTT1/GSTM1. At the same time, increasing amount of data are being published about the role of epigenetic mechanisms (aberrant methylation and imprinting alterations) in defective spermatogenesis.Materials and methods. We have studied 49 sperm samples obtained from unrelated infertile men using polymerase chain reaction, fragment analysis, and sequencing.Results. Five patients were excluded from the initial cohort: one with a repeat length of 29 (CAG) in the first exon of the AR, three with null genotypes in the GSTT1 and GSTM1, and one with the delF508/5T heterozygous compound in the CFTR. Thereafter, methylation of the imprinted gene SNRPN was determined using methyl-specific polymerase chain reaction and bisulfite sequencing. Aberrant SNRPN methylation was detected in 11.4 % of male infertility samples. In total, molecular genetic and epigenetic alterations were determined in 20 % of patients.Conclusions. Obtained data demonstrate a significant proportion of (epi)genetic disorders in a heterogeneous cohort of men with reduced fertility.