Tests to diagnose learning disabilities, autism, blindness using a child's whole genome could become a reality in clinics by 2011

From BioNews:

Tests to diagnose learning disabilities, autism and blindness using a child's whole genome could become a reality in clinics by 2011, according to a leading Dutch academic.

Professor Joris Veltman, an Associate Professor in Genomic Disorders from the Radboud University Nijmegen Medical Centre is already trialling the tests at his clinic. Professor Veltman's tests use next generation DNA sequencing machines, which he has adapted for use in genetic testing. Current genetic tests look at mutations in a few genes. But next-generation DNA sequencers allow all human genes to be quickly decoded, by a method called exome sequencing.

This has been key to understanding the cause of rare diseases like Schinzel-Giedion syndrome, which has mental retardation as one of the clinical features. Using exome sequencing, Veltman's team recently showed that this condition is caused by different mutations in a single gene, called SETBP1.

'In many cases, exome sequencing allows us to make diagnoses simply and quickly', he says. 'It is changing dramatically the way we do genetic diagnoses'.

The new technique can also be used to advance scientific research into other genetic diseases. By sequencing all a child's coding DNA and comparing it to DNA from healthy parents, Professor Veltman's team can identify unique mutations in DNA that aren't present in a child's parents.

'We can identify de novo - those that aren't present in the parents - mutations or deletions and link these to disease even if they have never been seen in other patients before', he says. Some genetic disorders are caused by missing or 'deleted' sections of DNA.

Professor Veltman warns this technique will initially be expensive, but predicts it will become cheaper as it becomes more widespread.

'At the moment, this is still expensive. We now talk about exome sequencing costing a few 1000 euros. For diagnostic use, we need each test to cost less than 1000 euros', he says. 'But with upscaling, we see this as a possibility in the near future. In the Netherlands, it will be possible to start doing this diagnostically by 2011'.