A team of researchers, led by academics from UNSW and St Vincent's Hospital, have made a discovery that transforms our understanding of genetic diseases.
The researchers, led by UNSW Professor of Medicine Robyn Ward, who is an oncologist at St Vincent's Hospital, have discovered an entirely new pattern of disease inheritance, which already has implications for people with a family history of bowel, ovarian and uterine cancers. Some individuals from these families may now, upon the recommendation of a genetic counsellor, decide to undergo further tests to determine the likelihood of them developing the diseases.
The paper, which has been published in the prestigious New England Journal of Medicine, includes one family with a history of bowel cancer as an example of what is called "epigenetic inheritance".
The mother, who had had bowel cancer, had three sons. Previous tests would have deduced that all three children had not inherited their mother's faulty gene and were not at risk of developing cancer. But instead, this research found that one of the children had a predisposition to bowel cancer.
"This is the first example in which a disease-causing defect has been inherited by a chemical attached to the DNA only, rather than a change within the DNA sequence itself, or a combination of the two," said the lead laboratory researcher, UNSW geneticist, Dr Megan Hitchins.
DNA is naturally decorated with chemical tags, but sometimes they are mistakenly attached to a cancer-prevention gene. This causes the gene to be switched off and as a consequence, cancer develops.
The researchers overturned the previously held belief that tagged DNA can not be inherited.
"This case shows that this type of gene fault mistake can be transmitted from one generation to the next, but in a highly unpredictable pattern, in contrast to the predictable manner in which faulty mistakes within the gene's code are transmitted," said Dr Hitchins.
"This will change who and how we assess for the likelihood of transmission of disease from one generation to the next," said Professor Ward. "Although these appear to be quite rare, it is important to take these findings further to look at their application to other familial diseases."
Members of the public who wish to find out more should contact their family cancer clinic
The research has been funded by the National Health and Medical Research Council.