Genomic imprinting, uniparental disomy and foetal growth.

Genomic imprinting is an epigenetic phenomenon identified in the past 15 years. Thus, maternally imprinted genes are only expressed from the paternal allele and vice versa. The mechanism of imprinting is still far from certain, but most probably it involves differential methylation of specific sites in or near imprinted genes. Disrupted imprinting can lead to phenotypic changes, and an increasing number of resultant clinical disorders are being identified. Many of these conditions involve disordered growth and/or development, particularly prenatal.