DNA sequencing has identified difficult-to-diagnose diseases in humans – the first time the technology has been used in a clinic.
The technique, which decodes thousands of genes simultaneously, has been used in laboratories to uncover genes related to diseases since 2009.
Now it has successfully moved to the clinic, where patients do not know what is wrong with them and may not know their family history of disease, and clinicians have few clues about which genes might be causing the problem.
Mitochondrial diseases, which affect the way the body produces energy, are notoriously difficult to diagnose. Found in at least one in every 5000 people, the diseases often involve many genes, and symptoms vary across organs. For example, common manifestations can include blindness, seizures, slow digestion and muscle pain.
Currently, diagnosing such disorders can take months or even years, and involves an invasive muscle biopsy. DNA sequencing technology may help to speed things up.
Researchers from Childrens Research Institute in Sydney, Australia, along with researchers from Harvard Medical School, sequenced the genomes of 42 children who had traits that suggested they carry a mitochondrial disorder. To work out exactly which disorder each child carries, the team looked both at the DNA in their mitochondria and at the 100 or so genes within their nuclear DNA that have already been linked to mitochondrial diseases. They also looked at a further 1000 nuclear genes that play a part in mitochondrial biology.
To distinguish between harmless genetic variations and those that might cause a disease, the team compared the patients’ genomes with databases of genetic variation recorded in the general population.
Ten of the children had mutations in genes previously linked to mitochondrial diseases, and so could be given a precise diagnosis. Mutations not previously associated with any disease were found in another 13 children. Tucker says that these patients can expect a full diagnosis once studies confirm the function of these genes.
Researchers say that the diagnosis rate “will improve” within the next couple of years as the list of genes known to be linked to mitochondrial diseases grows, and it becomes clearer how mutations combine to cause diseases.
In the future, when we have a much more thorough understanding of how a majority of human genes work and where the mutations are that produce malfunctions, this information will certainly prove very useful. However, in the near term when there is still so much about the function of genes we don’t know, how useful will access to DNA sequencing be?
Modern Health Perspectives believes DNA sequencing will become mainstream within the next five years. Overall, our health and well-being will improve significantly as a result.
Modern Health Perspectives