Methylation Status of Imprinted Genes and Repetitive Elements in Sperm DNA from Infertile Males

Stochastic, environmentally and/or genetically induced disturbances
in the genome-wide epigenetic reprogramming processes during male
germ-cell development may contribute to male infertility. To test
this hypothesis, we have studied the methylation levels of 2
paternally (H19 and GTL2) and 5 maternally methylated (LIT1, MEST,
NESPAS, PEG3, and SNRPN) imprinted genes, as well as of ALU and
LINE1 repetitive elements in 141 sperm samples, which were used for
assisted reproductive technologies (ART), including 106 couples
with strictly male-factor or combined male and female infertility
and 28 couples with strictly female-factor infertility. Aberrant
methylation imprints showed a significant association with abnormal
semen parameters, but did not seem to influence ART outcome. Repeat
methylation also differed significantly between sperm samples from
infertile and presumably fertile males. However, in contrast to
imprinted genes, ALU methylation had a significant impact on
pregnancy and live-birth rate in couples with male-factor or
combined infertility. ALU methylation was significantly high-er in
sperm samples leading to pregnancy and live-birth than in those
that did not. Sperm samples leading to abortions showed
significantly lower ALU methylation levels than those leading to
the birth of a baby. Copyright (C) 2011 S. Karger AG, Basel