# An allele-resolved nanopore-guided tour of the human placental methylome

## TL;DR

This study uses nanopore sequencing to explore the placenta's unique epigenetic and genetic features, revealing allele-specific methylation and new imprinted genes important for healthy pregnancy.

## Contribution

The study introduces a comprehensive, allele-resolved methylome of the placenta using nanopore sequencing and identifies novel imprinted genes.

## Key findings

- Nanopore sequencing revealed a detailed placental methylome with allele-specific methylation patterns.
- Novel imprinted genes ILDR2 and RASA1 were identified, which may be critical for placental and fetal development.
- The study found both conserved and individual-specific differentially methylated regions (DMRs) in the placenta.

## Abstract

The placenta is a temporary organ present during pregnancy that is responsible for coordinating all aspects of pregnancy between the mother and fetus. It has a distinct epigenetic, transcriptomic, and mutational landscape with low levels of methylation, high numbers of transcribed loci, and a high mutational burden relative to somatic tissues. We present this landscape through the application of nanopore sequencing technology to provide a more comprehensive picture of female placental genomics and methylomics along with integrated haplotype-resolved transcriptomic analyses across eight trios. Whole genome sequencing of trios allows robust phasing, permitting comprehensive genome-wide investigation of parent-of-origin methylation and transcription. This enhanced view facilitates identifications of many differentially methylated regions (DMRs), both conserved and differing between individuals, as well as previously unreported imprinted genes including ILDR2 and RASA1 which are potentially important for healthy placental and fetal development.

The placenta is a crucial organ required for human pregnancy which has a unique epigenetic and gene expression landscape. Here, the authors have applied nanopore whole genome sequencing technology to provide a comprehensive map of the placental methylome focused on allele-specific effects.