The genes in male and female placentas exhibit significant differences in expression, according to research conducted by the National Institutes of Health (NIH) alongside other institutions. These variations are linked to specific DNA tags known as methyl groups, which can turn genes on or off without altering their structure. This discovery may inform future investigations into the increased risk of pregnancy complications involving male fetuses, such as stillbirth and prematurity, as well as health conditions in adults born from complicated pregnancies.
The research team analyzed placental samples to identify differences in methylation patterns between male and female placentas. They discovered 2,497 new DNA sites with varying methylation patterns and reconfirmed over 2,500 sites from past studies. A large proportion of increased methylation occurred in male placentas (66.9%), with the remaining 33.1% found in female placentas. In males, these increases were associated with larger neonatal size, while in females, it related to greater placental size.
Notably, increased methylation near the CCDC6 gene was observed in male placentas and linked to preterm birth. Higher methylation levels near the FNDC5 gene correlated with reduced gene expression in males. FNDC5 is important for producing irisin, which protects against placenta damage. Decreased levels of irisin have been linked to preeclampsia, a condition characterized by high blood pressure during pregnancy.
Variations in the expression of ATP5MG and FAM83A genes in female placentas have been linked to conditions such as asthma, hay fever, eczema, and an increased risk of breast cancer. Genetic factors contribute to health differences between sexes from birth into later life, with male fetuses growing faster but facing a higher risk of complications such as preeclampsia, inadequate growth, and preterm birth.
The study was led by Dr. Fasil Tekola-Ayele from the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and is published in Nature Communications.
"Fasil Tekola-Ayele, Ph.D., is available for comment on this study."
Tekola-Ayele F, et al. published the paper "Sex-differentiated placental methylation and gene expression regulation has implications for neonatal traits and adult diseases" in Nature Communications.
The NICHD focuses on research and training to understand human development and improve reproductive health. The NIH is a principal federal agency for medical research and is part of the U.S. Department of Health and Human Services.
For further information, visit the NICHD and NIH websites.
