Exome sequencing

Next-generation sequencing is starting to gain a stronger foothold in clinical settings due to improvements in speed and accuracy and decreased costs. More specifically, enhanced diagnosis of neurogenetic disorders in children and adults has the potential to lead to better care for people with rare diseases like spinocerebellar ataxia, leukodystrophy, spastic paraplegia, as well as a host of other conditions.

Whole exome sequencing (WES) involves determining all of the expressed genes in an individual's genome. When used in concert with a complete patient evaluation and family medical history, the approach can help doctors identify disorders that may have gone undiagnosed for years.   

WES is more efficient and less costly than the type of genetic testing that has been more commonly used—and proper diagnosis can often put a name to a condition that patients have suffered from for years.

Now, a new study from researchers at the UCLA David Geffen School of Medicine, discusses the role of clinical exome sequencing in neurologic disease, including its benefits to patients, limitations, appropriate use, and billing.

Initially, many insurance companies balked at paying for the unproven technology. However, the growing body of evidence supporting the utilization of the test, and the demonstrated benefits to patients, should lead to greater insurance coverage of the test.

“Despite extensive literature supporting the use of this technology, many insurance companies still consider it to be investigational and may refuse coverage,” explained lead study author Brent Fogel, M.D., Ph.D., assistant professor of neurology and human genetics at the UCLA School of Medicine. “Our article outlines the appropriate use, benefits, and limitations of exome sequencing that these companies need to consider when making coverage decisions.”

The findings from this study were published recently in Neurology: Clinical Practice through “Clinical exome sequencing in neurologic disease.”

In previous work by Dr. Fogel and his colleagues using WES, the researchers found that 20 percent of a group of people with spinocerebellar ataxia could be diagnosed immediately using the technique and useful genetic information could be identified in more than 60 percent of the subjects, regardless of their age when the disease began or their family history.

“Clinical exome sequencing (CES) can be cost-effective due to its high diagnostic yield in comparison to other genetic tests in current use and should be utilized as a routine diagnostic test in patients with heterogeneous neurologic phenotypes facing a broad genetic differential diagnosis,” the authors concluded. “Moreover, CES can eliminate the need for escalating sequences of conventional neurodiagnostic tests.”

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