22 February 2016
ByAppeared in BioNews 840
A new blood test has been developed that can accurately detect all genes known to cause inherited heart conditions, say scientists.
They claim that the test – which looks a 174 genes related to 17 heart defects – is quicker and more accurate than previous tests, and would therefore be much cheaper to roll out.
'Genetic tests are invaluable when managing inherited heart conditions. They can help to make the initial diagnosis, and to choose the best treatment for the affected person. But where they make the biggest impact is in looking after that person's family,' said study author Dr James Ware, consultant at Royal Brampton Hospital.
'When a genetic test reveals the precise genetic abnormality causing the condition in one member of the family, it becomes simple to test other family members. Those who do not carry the faulty gene copy can be reassured and spared countless hospital visits,' he added.
The research was published in the Journal of Cardiovascular Translational Research, and the test is already being used at the Royal Brampton and Harefield NHS Trust, with 40 patients a month now being tested for genetic heart conditions.
Around half a million people in the UK are affected by inherited heart conditions, each of which has a different treatment, so it is important to identify the exact condition and gene that is causing it. For many people, they first become aware of the disease only when a member of the family dies suddenly and without obvious cause.
Currently, clinicians can use whole-genome (WGS) or whole-exome sequencing (WES) to look for genetic variants that might be responsible. However, these methods do not provide an equal depth of information - or coverage - of all genes, often meaning additional sequencing is needed to 'fill in the gaps'. The current test instead uses a targeted gene panel of the 174 genes known or suspected to cause heart conditions.
The study compared WGS and WES with the new test, looking at the DNA of 348 individuals. The new test detected 40 out of the 43 genes known to cause heart problems with 100 percent coverage, whereas the older method was only able to detect 36 out the 43 genes with coverage of between 49 and 98 percent.
The researchers also say that the new test should be much cheaper than the other methods, and it took only four days instead of nine to complete.
Professor Peter Weissberg, Medical Director at the British Heart Foundation, who was not involved in the research, told the Guardian: 'In this rapidly evolving field of research the aim is to achieve ever greater diagnostic accuracy at ever-reducing cost. This research represents an important step along this path.'
But Dr Yalda Jamshidi, Senior Lecturer in Human Genetics at St George's University of London, was cautious of the research findings. She told OnMedica: 'The new panel is more comprehensive than existing smaller DNA test panels. However, ultimately the difficulty with screening more and more genes will be in accurately determining which of the variants identified are indeed responsible for the disease.'