Using RNA sequencing for identifying gene imprinting and random monoallelic expression in human placenta

Imprinted genes showed consistent expression from either parental allele, as demonstrated by the SNP content of sequenced transcripts, while monoallelically expressed genes had random activity of parental alleles. We revealed 4 novel possible imprinted genes ( LGALS8 , LGALS14 , PAPPA2 and SPTLC3 ) and confirmed the imprinting of 4 genes ( AIM1 , PEG10 , RHOBTB3 and ZFAT-AS1 ) in human placenta. The major finding was the identification of 4 genes ( ABP1 , BCLAF1 , IFI30 and ZFAT ) with random allelic bias, expressing one of the parental alleles preferentially.

The main functions of the imprinted and monoallelically expressed genes included: i) mediating cellular apoptosis and tissue development; ii) regulating inflammation and immune system; iii) facilitating metabolic processes; and iv) regulating cell cycle.