February 20, 2007

First Fruits of Genome Wide Search Published for Sporadic ALS

[Quick Summary: Initial findings by the genome screening project funded by The ALS Association and partners show 34 genes linked with sporadic ALS now published online and available to build progress.]

Scientists funded in part by The ALS Association to find genes involved in the risk or cause of amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s Disease) have published initial findings on 34 genes in Lancet Neurology, making information freely available to the public and scientists through the National Institute of Neurological Disorders and Stroke (NINDS) Human DNA and Cell Repository web site at Coriell Institute for Medical Research, Queue at Coriell and Coriell Institute.

As presented at the 17th International Symposium on ALS/MND at Yokohama, Japan and now published online, the search so far suggests these 34 possible gene changes might be linked to risk for the disease. Further research must confirm these possible associations that are revealed through use of the most modern gene finder chips.

Clues gathered by the scientists at the National Institutes of Health, led by Bryan Traynor, M.D., in collaboration with investigators at the Robert Packard Center for ALS Research at Johns Hopkins, and in Italy, are the first fruits of collaborative genomic study of sporadic or spontaneously arising ALS. For more information, visit PubMed.

ALS now joins other diseases in which a genome wide search is uncovering important new clues for therapy. The report “truly marks a new time in ALS research,” said Lucie Bruijn, Ph.D., science director and vice president of The ALS Association. “Thanks to new technology, we can now focus on the sporadic form of the disease and tease out the disease mechanism.”

She noted that the study capitalized on the recently established repository at Coriell that mobilized the ALS community to contribute samples.

"We are delighted that this study has been published and even more delighted that the data and the samples are freely available,” Bruijn said. “This will facilitate others to work on this terrible disease and, in this new era of genomic research, this is clearly the way research must move forward."

A few known mutations produce a few percent of ALS cases, those passed in families.

For the vast majority of ALS cases that are not inherited, no single gene change emerged from the genome wide search. "There is no single gene out there which causes most of sporadic ALS,” Traynor said, “but we now have many leads to follow up in collaboration with our Italian colleagues."

The team has so far searched the genes of 276 sporadic ALS patients and an equal number of neurologically normal people. The scientists looked for sign posts in the genome, so-called single nucleotide polymorphisms (SNPs). These in turn indicated where in the genome differences might reside.

Gene finder chips report that one spelling of a gene sequence is more or less common in the people with the disease, compared to people without it. Variation in a gene might lead to increased risk for disease. Or the variation might be silent, producing no functional change.

Traynor pointed out that despite the statistical tests used to determine that 34 gene variants are significantly associated with the disease, chance alone could have produced the associations. “The next step,” he said, “is to go back and figure out which of these ‘hits’ are real and which are false.”

He also noted that the gene variants that came out of the study so far “represent only the tip of the iceberg. There are thousands of other SNPs that are less significantly associated with ALS but may ultimately turn out to be just as important."

The study has proceeded rapidly thanks to the successful and continuing collection of samples of ALS patient DNA to fill the repository at Coriell. The repository was established through NINDS. ALS patients and caregivers can donate anonymously a small amount of blood and give clinical history to aid in the gene hunt.

Funding of the study continues through a partnership of The ALS Association, with generous contribution from Lawrence R. Barnett, the Robert Packard Center for ALS Research at Johns Hopkins University, and two components of the National Institutes of Health:  the NINDS and the National Institute on Aging.

See The ALS Association’s web site under the research tab for further information about the genetics of ALS.