Imprinted genes are expressed monoallelically depending on their parental origin. High
expression of the majority of imprinted genes tested to date has been demonstrated in
extraembryonic tissues; placenta and yolk sac. Several mouse models where specific
imprinted genes have been disrupted demonstrate that fetal and placental growth may be
regulated by imprinted genes, in which paternally expressed genes enhance, and
maternally expressed genes restrain, growth. We review the current information on, and …