Will a gene bring healthful blessings or the curse of disease? It may depend on whether it is inherited from mom or dad, researchers reported on Wednesday.
A team at Iceland's Decode Genetics Inc found mutations in five disease-related genes that only take effect if inherited from a certain parent.
One, a new gene associated with diabetes, protects from the disease if inherited from the mother but raises the risk if inherited from the father. Three other diabetes genes also varied in their effects, but less so, depending on which parent it came from, the researchers reported in the journal Nature.
"We could make this discovery because we are in the unique position of being able to distinguish what is inherited from the mother from what is inherited from the father," Kari Stefansson, chief executive officer of Decode, said in a statement.
They found a gene that slightly raised the risk of breast cancer when inherited from the father but had no effect, or perhaps was slightly protective, when inherited from the mother.
A gene associated with a slow-growing form of skin cancer called basal-cell carcinoma was far more dangerous when inherited from the father.
The researchers were struck the most by the newly discovered type-2 diabetes gene, a so-called single nucleotide polymorphism or SNP — a single-letter change in the genetic code.
"The impact of the type-2 diabetes variant is not only large, but unusual: if an individual inherits it from their father, the variant increases risk of diabetes by more than 30 percent compared to those who inherit the non diabetes-linked version,' the researchers wrote.
"If inherited maternally, the variant lowers risk by more than 10 percent," they added.
"Nearly one quarter of those studied have the highest risk combination of the versions of this SNP, putting them at a roughly 50 percent greater lifetime risk of diabetes than the quarter with the protective combination."
For the study, the Decode researchers looked at the genes of 38,167 Icelanders, whose unique genetic heritage has changed little since the Vikings arrived more than 1,000 years ago.
The company filed for bankruptcy protection in November after its drug development programs stalled and sales for its DNA tests for diseases failed to bring in much cash.
Stefansson nonetheless believes the company has a product to sell, based on its unique genetic science.
"This we can do because of the large amount of data we have assembled on the Icelandic population," he said.
"We can use these tools to discover and integrate rarer variants into our tests and scans, identify drug targets for licensing, and put our know-how at the disposal of our service customers."
Two of the seven genes the company's scientists looked at, one associated with prostate cancer and another with coronary artery disease, did not seem to be affected by which parent's gene was inherited.
People inherit two copies of each gene, one from the father and one from the mother. A well-known process called imprinting affects which version of a gene is activated but this had mostly been known to activate genes during growth and development.