Genetic study helps investigators solve medical mysteries

December 31, 2015

In another study published in the January, 2011 Journal of the American Medical Association (JAMA). Dr. Foulkes details a second solved mystery involving five families with a long history of nontoxic multinodular goiter (MNG). Goiter is a thyroid disease which can lead to extreme swelling of the neck or larynx. The most common form of the disease is not genetic and is due to iodine insufficiency. However, this form of MNG was known to be genetic, but to date, no one had ever localized the specific gene or mutation responsible. Dr. Foulkes, Dr. Marc Tischkowitz (from the Program in Cancer Genetics and the Lady Davis Institute) and their team finally succeeded, and found the mutation in a surprising place.

As it turns out, the mutation, in a gene called DICER1, was extremely unusual, Foulkes said, who is also James McGill Professor of Medicine, Human Genetics and Oncology and Director of the Program in Cancer Genetics at McGill University. "It changes the protein in only one place, and that single change is enough to trigger multinodular goiter. Generally speaking, when you have a mutation in a disease gene, it causes a multitude of problems, not just one illness. But in this case, we have no evidence that it causes anything except goiter.

Intriguingly, women in three of the families had been diagnosed with an unusual type of ovarian tumor called Sertoli-Leydig Cell Tumor and thus Foulkes and his colleagues were able confirm that there is a genetic link between multi-nodular goiter and these rare tumors. This link had first been postulated in 1974.

"In the future, our challenge as researchers is to be able to help people with an unknown condition by finding out rather quickly what the genetic cause of their problem is" explained Foulkes. "We can hope in the long-term to have an impact on treatment, diagnosis and other aspect of management."

Source: McGill University Health Centre