Genetic testing can leave families uncertain

19th October 2016

Genetic testing of young people who die suddenly from heart diseases can lead to their families being left in an uncertain situation, a new study says.

The likely cause can be found in 16 per cent of deaths, a “plausible” cause in 24 per cent and a “speculative” discovery in 28 per cent of cases.

But that left nearly a third of cases unsolved. Thirty-two percent of the time, the researchers found no link whatsoever between sudden death and DNA, said Ali Tokamani  who co-authored the study from the Scripps Translational Science Institute in America and medical examiners in San Diego.

The study, published Tuesday in Journal of the American Medical Association used gene sequencing to analyse 25 cases of unexpected sudden death in people aged 45 or younger. The researchers wanted to pinpoint genetic mutations that could have caused the death, and give that information back to family members who may also carry the mutation.

Dr Torkamani, assistant professor and director of drug discovery, said the approach was relatively new so it was possible that he and his colleagues had missed relevant gene mutations due to a shortage of existing data on the topic. But, he said: "a lot of the answers are not as clear as one would hope they would be."

He said he was also surprised to find that 70 percent of the mutations were also found in a parent who had not died suddenly. In other words, these mutations weren't entirely new — and could have been in a family's DNA for generations.

"That actually makes it a little more challenging to identify the cause of death," Dr Torkamani said. "Because now you have living family members with what we believe to be the disease causing mutation, but they appear to be perfectly normal and healthy."

This ambiguous situation could lead to complicated questions for surviving family members. Should they get tested to find out if they also carry the mutation? And if they do have it, are there any steps they can take to reduce their risk of sudden death? Will their health insurance cover the cost of these preventative measures?

Dardie Robinson, who took part in the study, discovered she also carries the mutation linked to her son's death. She has urged her other children to get tested and considered getting an internal defibrillator (ICD) to protect herself.

Dr Torkamani said the family members who took part in the study often just wanted to know what happened to their loved ones, regardless of their own genetic risk.

"They maybe get a sense of relief," Dr Torkamani said. "It helps provide a sense of closure when you can provide some information."

Cardiomyopathy support nurse Robert Hall said: “While this is a small study, it raises the issue that genetics does not always give a straightforward answer.”

For more details of the study, see here.