New chip can offer faster SNP analysis

Single nucleotide polymorphisms (SNPs) are of great value to scientists and pharmaceutical companies seeking a way to predict susceptibility to diseases and responsiveness to treatments on an individual basis. A new postage stamp-sized chip fabricated from silicone rubber, developed by the Institute of Physical and Chemical Research in Japan, is said to offer a cheaper and faster way of analysing SNPs compared with current techniques.

The chip will probe for a gene of known sequence in order to identify those individuals who carry a SNP that makes the gene slightly different. The chip is etched with a microscopic channel coated on the bottom with polymer molecules attached to DNA of the exact opposite sequence of the target gene.

To run the test, a genetic sample obtained from the patient is placed on the chip and voltage is applied to both sides to make the sample move from one end of the channel to the other. If the patient's gene is the normal version, the complementary DNA is attracted to the gene and retards its flow down the channel. If the patient has a SNP, the gene is not slowed down and travels relatively faster.

The new chip, a fluorescent microscope and a video camera are all the equipment needed to determine whether the patient has a SNP in the target gene. The test takes seconds, and the procedure can be completed in two to three hours. The chips cost less than ¥50, according to the researchers, and the whole diagnostic system assembled for around ¥200,000 ($1,700).