Genomic imprinting characterizes genes with a monoallelic expression, which is 
dependent on the parental origin of each allele. Approximately 150 imprinted 
genes are known to date, in humans and mice but, though computational searches 
have tried to extract intrinsic characteristics of these genes to identify new 
ones, the existing list is probably far from being comprehensive. We used a 
high-throughput strategy by diverting the classical use of genotyping 
microarrays to compare the genotypes of mRNA/cDNA vs. genomic DNA to identify 
new genes presenting monoallelic expression, starting from human placental 
material. After filtering of data, we obtained a list of 1,082 putative 
candidate monoallelic SNPs located in more than one hundred candidate genes. 
Among these, we found known imprinted genes, such as IPW, GRB10, INPP5F and 
ZNF597, which contribute to validate the approach. We also explored some likely 
candidates of our list and identified seven new imprinted genes, including ZFAT, 
ZFAT-AS1, GLIS3, NTM, MAGI2, ZC3H12Cand LIN28B, four of which encode zinc finger 
transcription factors. They are, however, not imprinted in the mouse placenta, 
except for Magi2. We analyzed in more details the ZFAT gene, which is paternally 
expressed in the placenta (as ZFAT-AS1, a non-coding antisense RNA) but 
biallelic in other tissues. The ZFAT protein is expressed in endothelial cells, 
as well as in syncytiotrophoblasts. The expression of this gene is, moreover, 
downregulated in placentas from complicated pregnancies. With this work we 
increase by about 10% the number of known imprinted genes in humans.