Exome Sequencing Will Help Diagnose Patients with Unknown Disorders

Pathologists and clinical laboratory professionals will be able to obtain more precise results using exome sequencing for clinical diagnostic purposes.

Columbia University (CU; New York, NY, USA) sequenced the exomes of 150 patients to diagnose unknown disorders during the past year. The primary goal of the program is to prove that sequencing the exomes of these patients is both clinically useful and cost effective in guiding physicians to a correct diagnosis. They succeeded in making decisive diagnoses in one-third of the cases.

Pathologists should note that some of the patients in the exome-sequencing program had been tracked for years at CU without a definitive diagnosis. This is why clinicians at the academic center in New York City see value in exome sequencing for selected patients.

Wendy Chung, MD associate professor for Columbia University’s Clinical Genetics Program, is heading a study aimed at proving the medical utility and cost-effectiveness of exome sequencing as a first-line diagnostic test. She believes that is essential in ensuring insurers continue to pay for it. Quoted in the GenomeWeb report, she said, “I think it’s an incredibly powerful tool.”

Among the first 150 genome sequencing cases were patients Prof. Chung had followed for years without the ability to make a definite diagnosis. Of these patients, Prof. Chung said that she had “a strong clinical sense that there was an underlying genetic problem.” A significant number of these cases suffered from neurological conditions, but also heart conditions, syndromic birth defects and hearing loss.

The team at Columbia University compared genomic services provided by four different laboratories to identify genomic sequencing facilities that offer the most efficient and comprehensive services. The laboratories were Ambry Genetics, Baylor College of Medicine Medical Genetics Laboratories, GeneDx, and Columbia’s own Personalized Genomic Medicine Laboratory

“The biggest problem that I’m seeing is one of capacity, declared Prof. Chung, noting that turnaround time for exome tests has been increasing. “Everyone is starting to realize how valuable this [exome testing] in fact is.” She stressed the importance of identifying efficient genome testing providers, pointing out that inefficiency might hamper wider adoption of exome testing.

Additionally, some laboratories were easier to work with in terms of billing policies and how insurance is handled. Overall, the Columbia team said it experienced the best service from GeneDx. That is because this lab offers re-analysis after a year, includes family members in the analysis, and handles insurance issues efficiently.

Chung predicts that exome testing will be used earlier in the diagnostic process than today. She noted that, to date, exome testing has been used after patients had gone through other diagnostic processes, including panel testing, micoarrays, and metabolic workups.

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