Gene's 'parent' link to disease risk

Non-profit Icelandic company deCODE genetics has published an article in Nature reporting that our chance of developing genetic disease can be different depending on whether we inherited the genes from our mother or father.

deCODE genetics, which is having to sell its assets after announcing bankruptcy a few weeks ago, has identified several DNA variants which appear to effect disease predisposition differently depending on their parent origin.

Parent genes having different effects through inheritance is not a completely novel idea. The process of genetic imprinting (when the sperm and egg DNA mixes some genes are chosen to be expressed whilst others are silenced) has shown us some examples of maternal versus paternal effects - for example, a gene variant on chromosome 15, when inherited from the father, can give rise to Prader-Willi Syndrome, whereas when taken from the mother it will result in Angelman syndrome. However both of these are rare mental retardation syndromes caused by a severe genetic mutation - deCODE has identified more subtle genetic variants that can have very different outcomes for the child if they are inherited from the mother or father.

One of these newly identified DNA variants shows a 30 per cent increase in the chance of developing diabetes type 2 if inherited from the father, whereas if passed on from the mother it actually appears to have a protective effect, decreasing the chances by 10 per cent.

Kari Stefansson, the chief executive of deCODE Genetics and one of the main authors of the study, explained the study, saying that 'it isn't just the sequence that matters, it can sometimes be which parent you get the sequence from as well'.

By deCODE utilising their expansive genetic database they have shown that parental genetics may have an even larger impact then many had first thought. The study has also found that earlier studies could have been wrong in their calculations as they did not factor it in. For example a previous study into a gene variant known to increase chances of breast cancer found the chance of cancer with this gene to be increased by seven per cent, but the deCODE group were able to show the chance was actually increased by 17 per cent if the gene was inherited from the father, and again some genetic protection if inherited from the mother.

'This paper brings to the forefront the real importance of genomic imprinting in disease susceptibility, which we miss a lot of the time,' said Randy Jirtle, an epigeneticist at Duke University in Durham, North Carolina, US.