Connecticut lab’s gene test can find more rare diseases
There are more than 7,000 rare disorders, and many cannot be diagnosed in a doctor’s office.
That’s why genetic sequencing is so important.
Now The Jackson Laboratory in Farmington, Connecticut, is able to sequence the entire genome, an advance that will roughly double the number of rare diseases that can be positively diagnosed.
Until next-generation genome sequencing became available about 10 years ago, there was no way for many rare disorders to be accurately diagnosed, according to Melissa Kelly, clinical laboratory director at the Jackson lab.
“There’s been studies on this actually, how many missed diagnoses patients will have prior to getting their actual diagnosis from a genome, and it’s something like seven,” Kelly said.
There are as many as 7,000 rare diseases, according to the National Organization for Rare Disorders.
A rare disease is one carried by no more than one in 200,000 Americans, and includes Duchenne muscular dystrophy, hemophilia, cystic fibrosis and Hodgkin’s disease, according to the organization’s database.
Not all rare diseases are genetic, but many are, Kelly said.
Sometimes sequencing is called for because of “unusual facial characteristics,” she said.
“It might be that their nose is a little misshapen or their forehead’s really tall,” she said. “Ears are rotated funny or something. So it’s just the facial features that are ‘normal.’ ”
The issues one patient has could resemble more than one disease, so until you know the genetic mutations, “you don’t really know, can you do anything about it. It’s just sort of a guessing game,” she said.
Before the whole-genome sequencing was developed, the best that nextgeneration sequencing could do was to sequence the exome, or the proteins in the gene, which, while it contains most of the information, is about 1.5% of the genome.
That yielded a positive diagnosis about 25% of the time.
“The rest of them are left on what we call the diagnostic odyssey,” Kelly said. “So they’re getting test after test after test, but never getting a diagnosis. And those are the perfect candidates for whole-genome sequencing,” which can get an answer at least 40% of the time.
The bottom line is to help families “who have been searching for oftentimes years to find the answers,” Kelly said. “Even when those answers mean it’s not treatable, and they really can’t do anything about it, to have
the answer is just invaluable to them.”
Diagnostic odysseys
One problem with genetic sequencing is the expense. Nextgeneration sequencing of just the exome can cost up to $4,000, according to Dr. Ed Neilan, chief medical and scientific officer of NORD, and the full genome sequence will cost much more than that.
A spokeswoman for The Jackson Laboratory issued a statement about pricing, saying, “While we do not comment on specific customer pricing since it can vary with testing volume and turnaround time requirements, as a nonprofit biomedical research institution, our focus is and always has been on improving human health. JAX endeavored to make this crucial testing available as cost-effectively as possible knowing the financial responsibility will, in many cases, be patient-based.”
Cat Lutz, vice president of Rare Disease Translational Center in Bar Harbor, Maine, believes every baby should have its genome sequenced in order to avoid the emotional pain and hardship families experience when they are faced with an unknown disease.
“I think it is economically possible,” she said. “You think about the cost of that sequencing compared to the cost of doctor’s visits, emergency room visits, and then the sustainability of the health care of a very sick child. I think it’s very worth it.”