During development, genes can be expressed from either the maternal or the paternal chromosomes, in a process known as genomic imprinting. Usually, one copy of the gene is not expressed. But how is this expression controlled? A new study shows that the crucial imprinting signal may be carried by differentially methylated genes. Moreover, expression from, say, a maternal gene, may be prevented by the production of an antisense transcript from the corresponding paternal gene.
- Wolf Reik
- Miguel Constancia
