Sunday, February 18, 2018

Predictive genetic testing


A CLOSE LOOK: Scientist viewing DNA gel used in genetics, forensic, pharma research, biotechnology and biomedical science.

Mark Fraser

ACTRESS Angelina Jolie’s decision to have a double mastectomy made news headlines last year but her reason for doing so placed the often controversial topic of gene testing into the spotlight. By means of ‘predictive genetic testing’, Jolie’s doctors were able to determine that she carried a mutation or faulty gene BRCA1, and they estimated that she had an 87 per cent risk of developing breast cancer and a 50 per cent risk of ovarian cancer. After having the double mastectomy, Jolie’s chances of developing breast cancer dropped from 87 per cent to five per cent.

“Genetic testing plays a pivotal role in the prediction, targeted therapy, response to treatment and prognostication or prediction for common cancers such as breast and colon cancer. There is a need to establish and develop testing in areas of great need in Trinidad,”said Dr Roma Rambaran, lecturer of molecular biology and chemical pathology at the Faculty of Medical Sciences, University of the West Indies (UWI).

“Breast cancer is the second most common cancer which accounts for almost 12 per cent of cancer diagnoses globally,” said Rambaran. “Of these cancers 90 per cent are sporadic, meaning they come out of the blue but five to ten per cent of the cancers are inherited, so they have a familial connection and a strong family history,” she added. “These inherited diseases are linked to mutations and the most important mutations are for the genes BRCA1 and BRCA 2.

“If an individual has a family history of these diseases (cancers) they can test for this mutation so that they can find out their risk for developing this cancer later on,” said Rambaran. “During the process of predictive genetic testing, a blood sample is taken and the DNA is purified from the sample.

“Such a genetic test is able to predict susceptibility up to 80 per cent risk and this risk actually increases with age,” said Rambaran.

Rambaran referred to a 2010 report which concluded that in Trinidad there were 25 deaths per 100,000 due to breast cancer in 2004.

“That is alarming. Such a report makes us concerned and predictive genetic testing is something we should be thinking about using here in Trinidad,” she said.

Rambaran and her colleagues Dr Allana Roach and Dr Christine Carrington addressed an audience on Thursday evening at Amphitheatre A at the Eric Williams Medical Sciences Complex on the topic: Understanding gene discovery and genetic testing. It was the first of a series of public lectures to be hosted by the Faculty of Medical Sciences.

“There are six different ways one can use genetic tests. First to confirm the disease or to confirm the diagnosis of diseases, secondly to help predict the risk for predisposition of diseases, for screening in our population, for ‘pharmacogenomics’ or genetics which would help scientists move into the direction of individualised or personalised medicine, and also for research,” said Dr Allana Roach, geneticist and lecturer at the Faculty of Medical Sciences, UWI.

But the big question remains: given the fact that genetic testing and research is done around the world, why hasn’t genetic technologies been readily or meaningfully integrated in our health-care system in Trinidad and Tobago?

“The reasons for that are multifaceted. One of the major concerns at the University of the West Indies is the ethical and social considerations of these tests,”said Roach.

What is it about genetic testing and research that makes it so unique and yet so controversial?

“First of all, your genetic information is personal; it is also permanent. You are born with your genetics, you can’t change it. While there may be mutations at different levels throughout your lifetime—your genetic code is more or less permanent,” explained Roach. “Your genetic information is predictive, it can reveal much about an individual and his disease risks—information that the individual or his family may not be aware of. It is also ‘pedigree sensitive’,”she added, “which means that this genetic information can not only give an insight into the individual and his immediate family, but also on previous generations and those to follow.

“If we are going to integrate these tests into our health-care system, we want to ensure that they are being done in an ethical and socially responsible way. As we endeavour to develop our own diagnostic lab, we want to ensure that our population is well aware and well educated about the impact of such a lab in our country,” she said.