Deregulation of imprinted genes has been observed in a number of human diseases 
such as Beckwith-Wiedemann syndrome, Prader-Willi/Angelman syndromes and cancer. 
Imprinting diseases are characterised by complex patterns of mutations and 
associated phenotypes affecting pre- and postnatal growth and neurological 
functions. Regulation of imprinted gene expression is mediated by 
allele-specific epigenetic modifications of DNA and chromatin. These 
modifications preferentially affect central regulatory elements that control in 
cis over long distances allele-specific expression of several neighbouring 
genes. Investigations of imprinting diseases have a strong impact on biomedical 
research and provide interesting models for function and mechanisms of 
epigenetic gene control.