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Collateral Knowledge
Whole genome sequencing can reveal genetic mutations responsible for complicated diseases, but it can also reveal other mutations. How much do patients want to know?
Illustration by Justin Renteria

By Julie A. Jacob

Hope and Martin Garcia were looking for answers. Their 8-year-old son, Rylan, was wracked with constant fits of vomiting and was diagnosed with cyclic vomiting syndrome when he was 2. He had spent 90 percent of his life in a hospital.

The Belvidere, Ill., couple turned to the Children’s Hospital of Wisconsin’s Genomic Medicine Clinic. The clinic’s whole genome sequencing analyzes a patient’s entire genetic sequence to search for mutations that might be the cause of the patient’s health condition. But because the process looks at the entire genome rather than a specific gene or small set of genes, results unrelated to the specific condition can be uncovered.

And then the question becomes: How much do you want to know?

The clinic, a collaborative project of Children’s Hospital of Wisconsin and the Medical College of Wisconsin’s Human and Molecular Genetics Center, opened in 2010. Since then, 23 children and two adults have been tested. Whole genome sequencing yielded diagnoses for about one-fourth of those patients.

Choosing to start the process is not always an easy one, and the clinic provides extensive pretest counseling for the patient’s family, says Regan Veith, a certified genetics counselor who works at the clinic. “There was no doubt in my mind that I wanted to proceed with it,” says Hope Garcia. “We were at the end of our wits to find out why Rylan was so sick.”

Rylan and his parents underwent a simple blood draw in January 2013. Hunting through 20,000-25,000 individual genes for the genetic abnormality that causes a medical problem is like “looking for a needle in a haystack,” says Veith, and it requires massive computer analysis, data storage and time. “This technology works best for people who have rare, unique presentations,” says Veith. “That’s where it gets the highest yield.”

Six months later, Rylan’s results were ready. Hope Garcia wanted to know everything that was discovered about Rylan’s genetic sequencing. From her perspective, knowledge is power, and the more she and her husband know, the better. 

Although whole genome sequencing can find answers, the answers aren’t always good. In a case outlined in the July 2013 issue of Science Translational Medicine, a couple found out the genetic mutation responsible for causing their infant’s liver disease also causes progressive neurological problems. Based on that information, the baby’s parents elected to not have their child undergo a liver transplant, and the baby died at 6 months old. “In this case, although there was no improved measured clinical outcome, the parents were reassured that the disease was incurable and that a liver transplant would not have prevented the child’s death,” the authors wrote in the commentary. 

Veith says such counseling covers the reality of secondary results. “Some only want to know the disease-causing entity and nothing else,” she says. “Some want to know everything, and everything in between.”

The Garcias learned Rylan had genetic mutations that were causing some of his developmental problems, including difficulties with walking and speech. The testing, however, did not find a genetic mutation responsible for triggering his bouts of vomiting. Nonetheless, Rylan’s parents are happy they did it. “It gave us more answers to Rylan,” Hope Garcia says. “It doesn’t change his treatment, but it gives us more answers to the big picture.”

This article appears in the October 2013 issue of Milwaukee Magazine.
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The Brain Trust
POSTED 4/1/2014