The document discusses epigenetic factors that contribute to imprinting diseases. It describes how epigenetic modifications like DNA and histone methylation establish parental imprints and regulate gene expression in a parent-of-origin specific manner. Alterations in these epigenetic marks can lead to imprinting disorders like Prader-Willi syndrome and Angelman syndrome, which are associated with changes in imprinted genes on chromosome 15. The authors investigate these diseases using methods like MS-PCR to analyze DNA methylation patterns.