Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Novel asthma study shows multiple genetic input required; single-gene solution shot down

19.01.2005


Researchers led by a Brigham and Women’s Hospital/Harvard Medical School team found that wheezing -- a key physiological component of asthma -- requires the interaction of genes in several locations. The work, involving multiple independent verification, demonstrates the complexity of the genetic predisposition to asthma.



The study, "Interacting genetic loci cause airway hyperresponsiveness," appears online in Physiological Genomics, published by the American Physiological Society. "We know that there are both genetic and environmental factors that cause people to develop asthma," Dr. Kate G. Ackerman, the lead researcher, stated. "We have now shown that the genetic inheritance of wheezing, one component of asthma, is extremely complex in our model. This suggests that the discovery of these genes in the human population will be difficult and will require a multi-locus approach."

After the study on the airway hyperresponsiveness (AHR) trait, Dr. David R. Beier, the laboratory leader, said: "In the specific case of asthma, hopefully these results will direct human studies to look for genetic influences in a combinatorial fashion." Using an elaborate mouse model, the researchers found that the wheezing trait unambiguously required the interaction of loci on different chromosomes, yet analysis of the individual chromosomes showed no significant association with wheezing. (A locus is a site on a chromosome where the gene for a particular trait is located.)


Overcoming ’negative’ results of 10 human genome asthma studies

The study, "Interacting genetic loci cause airway hyperresponsiveness," was conducted by Kate G. Ackerman, Hailu Huang, Hartmut Grasemann, Chris Puma, Jonathan B. Singer, Annie E. Hill, Eric Lander, Joseph H. Nadeau, Gary A. Churchill, Jeffrey M. Drazen and David R. Beier. The research appears in the online edition of Physiological Genomics, published by the American Physiological Society.

The Harvard researchers set out to try and determine some of the inherited aspects of asthma, which is becoming "increasingly common" and where "each patient with asthma may have a variable constellation of the different components, and each component" is itself complex. They note that "in over 10 large human studies employing genome-wide analysis to detect asthma susceptibility loci, only two significant linkages have been detected. Of these, only one has identified an association with a specific candidate gene."

Narrowing the genetic focus; "magnitude of effect"

In order to "definitively identify loci associated with a genetically complex trait" (airway hyperresponsiveness, or AHR), the team "used selection for a disease phenotype in a serial backcross" whereby offspring showing certain laboratory-induced asthma-like reactions to stimuli were then used for breeding the next generation. "In this strategy," they explain, "genomic regions that are causally associated with the trait are retained, while unassociated regions are highly likely to be lost as breeding proceeds."

After seven generations of this selective breeding, Ackerman et al. found that several regions derived from the hyperresponsive A/J mouse strain were retained in mice with elevated AHR. Contrary to expectations, they found "no apparent association between inheritance of any single locus with elevated naïve AHR in the phenotypically derived recombinant congenic line." However, according to Beier, "we were fortunate that the analytical approach we were using allowed us to check not just for association of a single locus, but for the possibility that there might be coordination or cooperation between elements involved."

Indeed, the paper reports: "We found a highly significant association with the trait when loci on both chromosomes 2 and 6 were inherited together." Put another way: "…when a pair wise scan for interactions was done, a highly significant association was found for the retained chromosome 2 and 6 regions."

Confirmation from independent project source

While noting "the theoretical possibility that this type of interaction could confound human genetic association studies," the researchers point out that: "A result with this magnitude of effect has not been previously shown using contemporary methods of linkage and association analysis."

Building on their surprising results, the Harvard group was able to test consomic Chromosome Substitution Strains (CSSs) generated by the Whitehead Institute and Case Western Reserve University. Beier noted that the Harvard mice had been selected to demonstrate AHR, but "the beauty of the CSS analysis was that even though their mice weren’t made specifically for airway phenotypes, they could be studied to correlate our results independently." The authors believe their study is one of the first instances in which CSSs have been utilized as a new tool to independently validate a quantitative trait linkage (QTL) analysis study.

Next steps and implications for human asthma research

The paper concludes: "The identification of genomic regions containing loci causally associated with AHR, and the demonstration that this trait requires their interaction, has important implications for the dissection of the genetic etiology of asthma in humans." The authors also identified several other areas where action is indicated:

  • Besides asthma, the authors say their "study has important implications for the genetic analysis of common diseases in a human population."
  • The retained regions on chromosomes 2 and 6 "have conserved synteny distributed among 7 human chromosomes. A comprehensive analysis of these regions using association analysis may prove fruitful for uncovering additional loci that contribute to" human asthma.
  • Since both mouse lines had a lesser degree of AHR than the parental strain, this "suggests the maximally severe phenotype depends on inheritance of more than the two interacting loci we have identified."

Mayer Resnick | EurekAlert!
Further information:
http://www.the-aps.org

More articles from Studies and Analyses:

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>