Sifting DNA Databases for the Right Diagnosis

In 1982, doctors told Jackie Smith’s parents to take the 3-year-old girl home and enjoy her while they could. Her rare muscle disease, likely passed on from a mutation in her parents’ DNA, would probably kill her before she was old enough to drive, they said. Smith, now 35, has lived in the shadow of that diagnosis her whole life, as a small army of physicians failed to diagnose what accounts for her weak limbs and turned-in ankles. This past February, Claritas Genomics gave her the answer in less than three weeks.

Although analysts can quickly sequence a person’s DNA for about $1,000, doctors don’t necessarily know what to look for in those gigabytes of data, because most genetic databases aren’t widely shared or indexed. About 25 million Americans have at least one of 7,000 Mendelian disorders—ailments caused by a defect in a single gene—and researchers have so far matched fewer than half with genetic culprits. Claritas is working to fill in the gaps by isolating specific genes and comparing them against databases of hundreds of thousands of people’s DNA compiled by analytics company WuXi NextCode.