Katie suffers from craniosynostosis, a disorder where the bones in the skull fuse before the brain has stopped growing. This results in restricted brain growth, causing intercranial pressure, as well as breathing and learning difficulties.
Scientists at the Wellcome Trust Centre for Human Genetics in Oxford sequenced Katie's entire genome along with the genomes of her parents, John and Maria, and identified a single DNA base change in a gene called HUWE1 on her X chromosome. Neither of Katie's parents has the mutation, meaning it must have occurred spontaneously. This information gives a firm diagnosis and assures the parents that the risk of the condition being passed onto further children will be very low. Confirmation of the disorder and the genetic flaw responsible will help with her genetic counselling, as well as providing accurate information on how it might affect Katie's potential children.
Mr Warner said the findings had come as a relief. 'Not having a firm diagnosis has been difficult', he said. 'We might now have a label that makes everything crystal clear'.
The cost of sequencing an entire genome is beginning to decrease but currently the NHS does not provide it as a diagnostic tool. Katie was referred to Professor Andrew Wilkie, a consultant clinical geneticist at the University of Oxford who specialises in craniofacial disorders. Professor Wilkie is involved in an Oxford research project supported by Illumina, a DNA sequencing company, which is sequencing the genomes of 500 people with serious diseases. The teams intend to use the information gathered to explore the potential for the use of whole-genome sequencing in the diagnosis and treatment of individual patients in years to come.
'This collaboration represents a remarkable and very important step toward using whole-genome sequencing for translational medicine — where a patient's individual genetic information can be used to make key healthcare decisions', said David Bentley, vice president and chief scientist at Illumina. 'We are excited to be working with Oxford on this effort. This collaboration also will help Illumina advance its technology to better meet the specific needs of clinical environments'.