Affymetrix has launched a collaborative initiative to use microarray technology to identify specific causative mutations in mentally retarded children.

Called the European Cytogenetic Research Initiative, the collaboration is between Affymetrix, the University of Nijmegen in the Netherlands, the University of Tuebingen in Germany and the NHS Regional Genetics Laboratory in Birmingham, UK.

Currently, cytogeneticists use karyotyping and FISH technologies to understand how deletions, amplifications and other chromosomal rearrangements lead to congenital abnormalities and mental retardation in children.

Affymetrix says its microarray platform provides a higher-resolution view of the genome than traditional cytogenetic solutions, enabling researchers to better identify causative mutations, copy number variants and loss of heterozygosity (LOH) information.

"Each year up to 30,000 children with learning difficulties will be tested in the UK alone using karyotyping and targeted FISH methods, and these technologies are only helping to resolve 5 to 10 per cent of cases," Dr Dominic McMullan, head of molecular cytogenetics at the NHS Regional Genetics Laboratory, said.

The collaborators said that by using the microarray technology, they expect to find a much higher number of causal de novo deletions and amplifications than with current methods.