New array sequences mitochondrial genome quicker

Affymetrix has launched its latest microarray sequencer, which enables researchers to identify genetic variations associated with diseases, forensics, population studies or stem cells, proving particularly useful in drug research and development.

The robust Affymetrix GeneChip Human Mitochondrial Resequencing Array 2.0 provides a complete picture of variation in the mitochondrial genome, while significantly reducing the time, labour and cost involved in sample preparation.

As proof of the technology's versatility and performance, researchers revealed they analysed the entire sequence of the mitochondrial genome in a single 48-hour experiment.

The array interrogates all 16,500 bases of the human mitochondrial genome with only three polymerase chain reactions (PCR).

This provides scientists with the most efficient and cost-effective method for detecting variants associated with genetic disease, forensics, population studies or stem cells.

"We get sequence data from the array about ten times faster than we do with conventional methods," said Bert Smeets, associate professor of Genetics at Maastricht University.

"Using the array in our studies of complex mitochondrial disease, we've discovered five known pathogenic mutations and more than 70 previously unknown genetic variations in patients, which allow us to explain the pathology in about 25 per cent of the patients. The whole-genome approach is helping us to understand this disease at a level of detail never before possible," he added.

The discoveries that this array reveals could lead to the complete sequence information for mitochondria on a single array that has relevance to a wide range of fields including disease genetics, forensic identification and population genetics.

Joseph Califano, associate professor of otolaryngology at Johns Hopkins University said: "There's an obvious increase in the number of mutations that can be detected with the second generation GeneChip mitochondrial array."

"To date, we've sequenced about 85 head-neck tumours with matching white blood cell DNA from those patients. So far, we've found a pretty impressive somatic mutation rate of close to 50 per cent in these tumours."

Over the last decade, DNA micro array technology has evolved to become a powerful tool with which scientists can analyse the expression level of thousands of genes simultaneously.

Alongside Affymetrix, Agilent Technologies and Applied Biosystems also produce products that contribute to the DNA microarray market - expected to reach $937 million (€751 million) by 2010.

Microarrays are most often used for various types of expression profiling. Scientists in core labs are more likely to use arrays in drug discovery research, high throughput screening, comparative genomic hybridisation (CGH) and SNP detection and diagnostics, reflecting their analysis of both DNA and RNA templates as well as the diverse needs of their internal customers.