Placental expression profile of the candidate imprinted genes. a Filtering 396 candidate imprinted genes for the inclusion to the high-confidence analysis for the parental allelic expression (details provided in Additional file 4: Table S3). The list of 300 human genes predicted to exhibit parent-of-origin determined allelic expression were retrieved from the Geneimprint database . The list was supplemented with 96 recently reported novel candidate imprinted genes in the human placenta [6, 14, 15]. b The analyzed geneset included 11 true imprinted genes with parent-of-origin-specific transcription, 14 genes with biased parental allelic expression, and 66 biallelic loci. c Expressional breadth across human tissues and d the abundance of placental transcripts of the analyzed genes stratified based on the parental allelic expression. Human tissue data was derived from the Protein Atlas database . FPKM, fragments per kilobase of transcript per million mapped reads; Mat, maternal; n/a, not available; Pat, paternal.