Sequencing Protein-making Part of Genome Can Change Diagnosis and Patient Care
In the June 13 issue of Science Translational Medicine, an international team led by researchers from the University of California, San Diego School of Medicine reports that the new technology of exome sequencing is not only a promising method for identifying disease-causing genes, but may also improve diagnoses and guide individual patient care.
In exome sequencing, researchers selectively and simultaneously target and map all of the portions of the genome where exons reside. Exons are short, critical sequences of DNA in genes that are translated into proteins – the biological workhorses involved in virtually every cellular function, plus various structural or mechanical duties.
The researchers, headed by principal investigator Joseph G. Gleeson, MD, professor of neurosciences and pediatrics at UC San Diego and Rady Children’s Hospital-San Diego, sequenced the exomes of 118 patients who had been diagnosed with specific neurodevelopmental diseases. In each of the cases, all known genetic causes of their disease had been previously excluded.
Not surprisingly, the scientists found that exome sequencing newly identified numerous disease-causing genes, including the identification of the EXOC8 gene as a cause of Joubert syndrome, a condition affecting the developing cerebellum, and GFM2 as a cause for a condition that results in a small brain combined with pediatric diabetes.
More surprising, the researchers discovered that in approximately 10 percent of cases, exome sequencing led to the identification of a known disease-causing gene, prompting a change in diagnosis and care for some patients.