Milwaukee Researcher Finds Multiple Genes at Play in Childhood Disorder

Nov 27, 2013

New research reveals many genes are behind the childhood apraxia.

A study by a Milwaukee researcher has identified additional genes related to a complex speech disorder affecting children, but the work could lead to a better overall understanding of defects in the human genome.

Worthey says often in genomic medicine, researchers are trying to address diseases that are believed to be caused by a single gene defect.

But Worthey wanted to look at more complex genetics, where multiple genes could be having an effect.

As director of genomic informatics for the genome medicine clinic at Children’s Hospital of Wisconsin and the Medical College of Wisconsin, Worthey studies genetic defects in childhood apraxia, and she knew that many in that field suspected several genes were involved.

So Worthey and her colleagues performed exome sequencing on 10 children. Exome sequencing is a cheaper, faster approach that only sequences a small percentage of the human genome.

"You get less data, but you get most of the pieces currently known associated with disease," she says.

The researchers found a number of different genes involved, including some new ones.

"It was kind of an accumulation of smaller changes that gave rise to the disease," she says.

What's significant about their findings, Worthey says, is that many of these genes shared the same "pathway" within a cell. And that could have big implications in terms of how treatment gets to the genes.

"It's the pathway going wrong that you treat with the drug," she says. "Finding more genes increases our knowledge about how broad and diverse that pathway is and it may even get us into other pathways that already have drugs for them that can be used in these cases potentially."

Worthey warns new drugs won't happen very quickly. But she says knowing how multiple genes and pathways contribute to a disorder can help doctors and researchers properly diagnose and treat children with a speech problem by ruling out other causes.

This research might not have been possible just a few years ago, Worthey says. Back in 2010, genomic researchers at Children's Hospital and the Medical College made news when they successfully used genome sequencing to diagnose and treat a child with a rare medical condition.

But even in the short time since then, sequencing technology has vastly improved. Computational capabilities - what's needed to sort through all that data gathered by sequencing - has also gotten much faster.

"When I started my PhD was really when genomics data was starting to be made available, and it took me three years to do what it would have taken me a week or less now," she says.

Worthey says researchers now find 50 to 60 new causal associations between genes and diseases every month, whereas in 2005, there were only 80 found a year.

But Worthey says challenges still remain in accessing the overwhelming amount of data sequencing produces.

"We now have a filter that we can put on the fire hose to get the data out of it that we can use just now to make diagnoses and understand what's going on," she says. "At the same time the rest of the data that's still in the fire hose is still data we need to treat anyone. We need to learn how to open it up a little bit to use that data."

Worthey's findings on genetic defects in childhood apraxia were published in the Journal of Neurodevelopmental Disorders.