What is epigenetic imprinting?

The molecular mechanisms responsible for imprinting are defined by the inheritance of epigenetic tags (see FAQ 7) from cell generation to cell generation and from the parents to their offspring. Classically, epigenetic imprinting, or silencing, is the suppression of certain genes on chromosomes, depending on from which parent they were received. When DNA is passed to daughter cells after fertilization of an egg by a sperm, certain alleles can become active only if they were received from the mother, others only if they came from the father. If a gene is suppressed through imprinting from one parent, and the allele from the other parent is not expressed because of mutation, neither can act and the child will be deficient. Genetic imprinting has also been defined as the gamete-of-origin dependent modification of phenotype.