The chances of you developing a disease can be different depending on whether you inherit the gene that impacts the disease from your mother or father. A study, published in the journal Nature, looked at the parental origin of gene variants and found five different disease-associated gene variants that had different and even opposing effects depending on parental origin. The same gene variant, when inherited from one parent increased the risk for disease, but it was protective if inherited from the other parent.
Normally, everyone inherits one gene from the father and one from the mother for every protein that is produced in the body. But with a small number of genes, either the father’s or the mother’s gene is silenced. This process is called “imprinting”. Imprinting is needed for normal development of the embryo. Previously, no one had looked at the association of imprinting and the development or risk for disease. The authors of the Nature publication write: “Although many associations between sequence variants and human traits have been discovered through genome-wide associations, the impact of parental origin has largely been ignored” (Kong, A. et al.).
The scientists at the non-profit Icelandig company deCODE genetics, studied the genes of more than 38,000 Icelanders and determined the parental origin of most of their genes. Then they focused on some genes with variations that were known to be associated with disease. They found five parental origin specific associations. One was breast cancer associated, another was related to skin cancer (basal cell carcinoma), and three were associated with type 2 diabetes. Interestingly, when one of the type 2 diabetes associated gene variant came from the father, there was a 41 percent increase in risk of disease, but when the variant came from the mother, it was protective and lowered the risk.
This study may be just the beginning for understanding the inheritance of genetic risk factors for disease. Imprinting of genetic variants may explain why some diseases skip generations. It is likely, now that the tools for imprinting of genetic variants are available, many more genetic risk factor will be found and assessed. One important area will be the association of genetic variants with mental illnesses.
Kong, A. et al. Parental origin of sequence variants associated with complex diseases. Nature (2009) 462:868.