Persistent epigenetic changes in adult daughters of older mothers

Women of advanced maternal age account for an increasing proportion of live births in many developed countries across the globe. Offspring of older mothers are at an increased risk for a variety of subsequent health outcomes, including outcomes that do not manifest until childhood or adulthood. The molecular underpinnings of the association between maternal aging and offspring morbidity remain elusive. However, one possible mechanism is that maternal aging produces specific alterations in the offspring's epigenome in utero, and these epigenetic alterations persist into adulthood. We conducted an epigenome-wide association study (EWAS) of the effect of a mother's age on blood DNA methylation in 2,740 adult daughters using the Illumina Infinium HumanMethylation450 array. A false discovery rate (FDR) q-value threshold of 0.05 was used to identify differentially methylated CpG sites (dmCpGs). We identified 87 dmCpGs associated with increased maternal age. The majority (84%) of the dmCpGs had lower methylation in daughters of older mothers, with an average methylation difference of 0.6% per 5-year increase in mother's age. Thirteen genomic regions contained multiple dmCpGs. Most notably, nine dmCpGs were found in the promoter region of the gene LIM homeobox 8 (LHX8), which plays a pivotal role in female fertility. Other dmCpGs were found in genes associated with metabolically active brown fat, carcinogenesis, and neurodevelopmental disorders. We conclude that maternal age is associated with persistent epigenetic changes in daughters at genes that have intriguing links to health.