Methylation screening of reciprocal genome-wide UPDs identifies novel human specific imprinted genes

Utilizing reciprocal genome-wide uniparental disomy samples presenting with Beckwith-Wiedemann and Silver-Russell syndrome-like phenotypes, we have analyzed ~0.1% of CpG dinucleotides present in the human genome for imprinted differentially methylated regions (DMRs) using the Illumina Infinium HumanMethylation27 BeadChip microarray. This approach identified 15 imprinted DMRs associated with previously characterized imprinted domains, and confirmed the maternal methylation of the RB1 DMR. In addition, we discovered two novel DMRs: a maternally methylated region overlapping the FAM50B promoter CpG island, which results in paternal expression of this retrotransposon, and a paternally methylated region located between maternally expressed ZNF597 and NAT15 genes. We analyzed reciprocal genome-wide uniparental disomy samples (one maternal UPD and three paternal UPD samples) and six different normal somatic tissues derived from the three germinal layers (lymphocytes, buccal cells, placenta, brain, muscle, and fat) .