Imprinted Genes Altered in IVF Embryos

At the 22nd annual conference of the European Society of Human Reproduction and Embryology on Monday, scientists reported that mice embryos resulting from in vitro fertilization could have genetic abnormalities due to different culture media and concentrations of oxygen. One of the genes identified, H19, is involved in Beckwith Wiedemann syndrome. It’s possible that laboratory culture conditions for the fertilization of eggs resulting in embryos alter imprinted genes; genes that differ in their expression depending on their inheritance from the mother or the father.

Five imprinted genes were identified which showed a significant difference in expression levels between IVF mouse embryos in culture and in vivo controls:

• Cd81- expresses a membrane protein with unknown function during embryogenesis. It is involved in T cell development (part of the immune system) and the hepatitis C virus binds to it to gain entry to cells.
• H19 – a developmentally regulated gene, thought to be a tumour suppressor and associated with Beckwith Wiedeman syndrome.
• Slc38a4 – plays a role in amino acid transport to cells.
• Copg2 – plays a role in transport of proteins within cells and is associated with Silver-Russell syndrome, a growth disorder occurring in 1 in 75,000 births (involves intrauterine growth restriction and subsequent poor growth).
• Gnas – plays a role in cell signalling and is associated with McCune-Albright syndrome (involves bone, hormone and skin abnormalities), pseudohypoparathyroidism Ib (involves inadequate levels of calcium and excessive levels of phosphates in the blood), and GH-secreting adenomas (type of tumour).

Keep in mind that these results are from studies of mice, but I suppose common sense would tell us that culture medium and conditions probably don’t simulate the natural fertilization process. Thus far, most children conceived by IVF appear to be healthy and not at greater risk of birth defects.

More about growth and metabolic genes in IVF children.

Medical News Today, June 22, 2006

Technorati Tags: ivf, embryos, imprinting, imprinted genes, genes, genetics, disease, health, dna, Beckwith Wiedemann