Genomic imprinting Flashcards
Genomic imprinting
Genomic imprinting refers to a situation where a piece of DNA can behave differently depending on whether it is inherited from the mother or the father. DNA sequences are marked (imprinted) in the ovaries and testes almost like a stamp which says where the sequence has come from, this stamp affects the expression of the sequence. The two classic examples in psychiatry include Prader-Willi and Angelman syndrome.
Prader-Willi is due to a deletion of chromosome 15q when inherited from the father. It is characterised by hypotonia, short stature, polyphagia, obesity, small gonads, and mild mental retardation.
Angelman’s syndrome (Happy puppet syndrome) is due to a deletion of 15q when inherited from the mother. It is characterised by an unusually happy demeanour, developmental delay, seizures, sleep disturbance, and jerky hand movements.
