The significance of genomic imprinting for brain development and behaviour.

Autosomal genes which are expressed according to parent of origin receive an epigenetic mark (imprint) when they pass through the germ line, and fail to obey the Mendelian Laws of gene expression. These imprinted genes have played an important role in mammalian evolution particularly in the context of mother-infant and infant-mother interactions. Imprinted genes are also implicated in a number of human clinical disorders, including Prader willi syndrome, the most common form of dysmorphic genetic obesity, which is characterised by infantile hypothalamic dysfunction which causes hyperphagia and hypogonadism. The way in which imprinted genes effect hypothalamic and placental development provide for co-adaptive traits between mother and foetus, ensuring that offspring which extract “good” maternal nurturing will themselves be both well provisioned for and genetically predisposed towards “good” mothering.