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October 2, 2003

Geneticist returns to the province
Solving puzzles

Dr. Terry-Lynn Young

Photo by HSIMS
This DNA sequencer, purchased with donations to the Newfoundland Cancer Treatment and Research Foundation, is invaluable to the work of molecular geneticist Dr. Terry-Lynn Young.

Molecular geneticist Dr. Terry-Lynn Young has returned to Memorial to continue her specialized work in medical genetics. Her current research interests include deafness and breast cancer.

Dr. Young earned her PhD in medical genetics from Memorial in 2000 under the supervision of Dr. Willie Davidson. Her interest in genetics was sparked by earlier work with Drs. Roger Green and Bill Fitzgerald on some of the big colon cancer families in the province.

“It made me realize how powerful genetics could be,” she said.

Bardet-Biedl Syndrome was the focus of her doctoral work, and during postgraduate training she developed further expertise in genetics and genomic approaches to gene discovery in deafness and breast cancer. She was a senior fellow at the Division of Medical Genetics, University of Washington, under the supervision of world-renowned breast cancer geneticist Dr. Mary-Claire King, discoverer of the BRCA1 gene (BReast CAncer susceptibility gene 1).

Dr. Young likes to work closely with clinicians and genetics counsellors, and that was one of the attractions of returning to Memorial.

“They collect family trees and blood samples, and then I take the blood samples, extract the DNA and look to the human genome for answers.”

In the laboratory, it’s often a long and sometimes tedious task to identify the gene and then the specific mutation that causes a problem such as hereditary deafness. Working on blood samples from a family identified along Newfoundland’s south coast by now-retired Memorial geneticist Dr. Elizabeth Ives, Dr. Young was able to identify the responsible gene.

“We took a huge family and narrowed it down to about 20 informative individuals. We had to be absolutely sure their deafness was the familial form and not caused by other factors like maternal rubella, infections, drugs or noise exposure. We go from a huge pedigree to a much smaller but much more informative pedigree. Then we get a set of 350 to 400 polymorphic markers and screen the families looking for a pattern that exactly fits the pattern of deafness in the family. It’s a puzzle and that’s part of the fun of it, solving the puzzle.”

The problem is that sometimes the puzzle doesn’t fit quite perfectly.

“If we find a family where the pattern fits for 10 of the deaf people but not for the eleventh then we go back and look for other reasons this person might be deaf to make sure we’re on the right track.”

Since the original study, two more Newfoundland families with hereditary deafness have been solved. Originally the blood work for the other two families was sent to the National Institutes of Health in Bethesda, Maryland, for laboratory work, but Dr. Young has subsequently visited the researchers there and taken over the work on one family. She’s recently been successful in identifying the mutated gene in this family and is collaborating with the NIH researchers to identify the mutation in the second family. At Memorial, she is continuing research on hereditary deafness with Dr. Bridget Fernandez and a team of hearing professionals from around the province.

In addition to her work on deafness, Dr. Young also has expertise in breast cancer genetics. Researchers have identified several genes that cause inherited susceptibility to breast cancer and women who inherit a mutation in either have a 40 to 90 per cent lifetime risk of developing breast cancer. During her work at the University of Washington, Dr. Young identified 11 mutations in genes in Newfoundland families with breast and/or ovarian cancer. Her interest in returning to St. John’s to continue this research was supported when the Newfoundland and Labrador Research and Treatment Foundation was able to purchase a DNA sequencer for her laboratory. She is now working with Drs. Jane Green and Kara Laning to look for new mutations and new cancer genes.

With the latest technology and “beautiful laboratory space,” Dr. Young is excited about being back at Memorial and continuing her work while expanding molecular genetic research in the province and teaching invaluable skills to students.


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Next issue: October 16, 2003

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