In non-imprinted regions of the chromosomes, the parental epigenetic marks are erased in the germ cells only to be newly established in a parental-specific manner.> Classic human disorders related to genomic imprinting are Prader-Willi syndrome (PWS), Angelman syndrome AS), Beckwith-Wiedemann syndrome (BWS), Russell-Silver syndrome (RSS), and Albright hereditary osteodystrophy.> A characteristic feature of all of these diseases is that they do not exhibit normal Mendelian patterns of inheritance as well as showing parental origin effects.> The normal role of imprinting seems to have evolved to fine-tune the growth and development of the fetus.SYNDROMES INVOLVING IMPRINTED GENESCHROMOSOMAL LOCATION* Beckwith-Wiedemann syndrome, BWS11p15* Prader-Willi syndrome, PWS15q11.2-q12* Angelman syndrome, AS15q11.2-q12* Russell-Silver syndrome, RSS7p11-p13, 7q31-qter* Transient neonatal diabetes mellitus, TNDM6q24* Albright hereditary osteodystrophy, McCune- Albright syndrome, PHP1b20q13* Familial nonchromaffin paraganglioma11q13* Maternal and paternal UPD14 syndromes14> In addition to the syndromes listed in the Table above several diseases that are the result of complex genetic involvement have been shown to exhibit parent-of-origin effects.> These disorders include autism, Hirschsprung disease, Alzheimer disease, schizophrenia, bipolar affective disorder, and type 1 and type 2 diabetes.">