A cheap, rapid and portable point-of-care genetic test could be a step closer thanks to a team of scientists from Japan and Thailand.

Single nucleotide polymorphisms (SNPs, pronounced snips) are genetic variations in a person's DNA sequence. They can indicate a susceptibility to disease and could be useful in predicting a patient's response to therapy. Now Eiichi Tamiya at the Japan Advanced Institute of Science and Technology in Nomi City and his team have developed a chip that can detect SNPs and used it to find the variations in a gene linked to Alzheimer's disease. 

Disposable chip detects DNA variations linked to Alzheimer's disease

The group used disposable printed chips to analyse DNA from human volunteers. Before analysis, the DNA sample is amplified with a segment of DNA corresponding to the SNP of interest. The DNA is then added to the chip, where it binds to a redox molecule. If the SNP is present, then the amplification step is successful and so a smaller current is measured by voltammetry. Importantly, the method does not require the redox molecule to be immobilised on the sensor. This helps make the chip system simpler and cheaper than existing SNP tests. The group went on to apply the method to detect SNPs linked to metabolism rate and alcohol breakdown.

The team aims to integrate the chip with its own DNA amplifier to convert it into a portable and user-friendly device for point-of-care tests. Philip Day, a genomics expert from the University of Manchester, UK, suggested that more development could lead to better amplification technology or even amplification-free diagnosis and eventually 'reduce or ultimately eliminate' the need for amplifiers on the chip. Day added that 'Tamiya's research could contribute to the highly sensitive detection of sequences, such as pathogens.' 

Tamiya said that the sensors 'have the potential to meet the need for inexpensive, rapid and hand-held systems for genetic analysis, diagnosing cancer predisposition, identifying genetically modified organisms, and reducing recent threats of bioterrorism.'

Edward Morgan