A method to speed up the genetic diagnosis of Huntington’s disease has been reported by Swiss researchers.
It is known that elongated segments of DNA cause Huntington’s disease and certain other disorders of the brain – but determining the length of this gene involves intricate laboratory work and takes more than five hours, according to the scientists.
Now, Swiss researchers at the University of Lausanne, working with scientists from Toulouse, say they have developed reliable method for measuring the length of the responsible DNA region, which yields a result in just five minutes.
The team extracted DNA from blood cells, amplified the specific region and determined its size with a newly developed chip, which holds two funnel-shaped chambers that are a fraction of a millimetre wide.
The researchers then applied voltage and pressure to these chambers to separate the electrically charged DNA fragments according to their size.
This resulted in the smaller fragments being pushed down the funnel. The researchers added fluorescent dye to detect the exact position of the fragments under a microscope and establish their length.
Professor Vincent Dion, of the University of Lausanne, said that the variable length of the DNA fragments is caused by a repetition of three nucleotides of the genetic code (CAG).
The mutation leads to destructive changes in the encoded protein and the protein produced by the mutated gene is toxic to brain cells.
Prof Dion said while healthy people have 35 or less of these repeats, most Huntington’s disease patients have 40 or more, which is why it is important to know the size.
“Our method is more sensitive and faster than the current methods”, says Vincent Dion.
R. Malbec et al: µLAS: Sizing of expanded trinucleotide repeats with femtomolar sensitivity in less than 5 minutes. Scientific Reports 10 January 2019; doi: 10.1038/s41598-018-36632-5
Leave a Reply