Researchers have uncovered 16 new genetic associations related to respiratory allergies caused by common allergens like pollen, dust-mites and cat dander. The findings come from the largest ever genome-wide meta-analysis of existing studies.
The symptoms of hay fever and other respiratory allergies plague a large proportion of the population in developed nations. As much as 20% of American children may experience allergic reactions to one or more allergens such as those mentioned above; the figure is slightly lower for adults but still significant. Genes implicated in the study highlight a series of key pathways in the biological basis of common allergies.
The study, conducted in collaboration between 23andMe, the leading personal genetics company, and the Avon Longitudinal Study of Parents and Children (ALSPAC), examined data for more than 53,000 individuals. The study also identified eight genetic variations for allergies that have previously been associated with asthma.
Allergies and allergic asthma are among the most common diseases in the industrialized world. In the United States, a 2005 survey showed that more than half of the population tested positive for sensitization to at least one of 10 common allergens, a considerable increase over results of the same survey performed approximately 10 years earlier.1
"We've seen some substantial increases in prevalence of allergies and asthma," said David Hinds, Ph.D., author and 23andMe principal scientist. "Although environmental factors certainly play a role, our study reinforces the genetic link between common allergens and a person's susceptibility to experiencing an allergic reaction. Additionally, current estimates of the heritability of allergies are high, which suggests that understanding the genetic factors underlying allergic conditions may be key to understanding who might be most likely to suffer from allergies and how the condition might best be treated."
The study, titled "A Genome-Wide Association Meta-Analysis of Self-Reported Allergy Identifies Shared and Allergy-Specific Susceptibility Loci" was published online on June 30, 2013 in Nature Genetics, a leading monthly, international scientific journal.
23andMe selected three common self-reported allergy phenotypes – pollen, dust-mite and cat allergies – for which comparable data was available both in the 23andMe research community and in a cohort from the Avon Longitudinal Study of Parents and Children (ALSPAC). Data from both organizations was then included in a genome-wide association meta-analysis.
"Allergy is an important component of many diseases, including asthma, eczema and hay fever, which together account for a huge burden on patients and the health services." said professor John Henderson of ALSPAC. "This is a very exciting time for allergy research. Genetic discoveries have identified specific pathways of allergy development that are not shared with allergic diseases like asthma. Understanding these pathways could lead to eventual development of drugs that cure or prevent allergy rather than just suppressing its symptoms."
"One of the key features of this work is the demonstration that with a suitably sized study, the analysis of medically relevant questionnaire data alongside genetic variation has the potential to yield important information concerning the underlying biology of a complex outcome," said Dr. Nic Timpson of ALSPAC. "Indeed, through this collaborative interaction with colleagues from EAGLE where specific tests of allergic sensitization were available, we were able to independently replicate many of the findings made here."
Also published on June 30, 2013 in Nature Genetics was a companion study called, "Meta-Analysis of Genome-Wide Association Studies Identifies 10 Loci Influencing Allergic Sensitization". This study had similar methodology to the 23andMe/ALSPAC study but was conducted by the Early Genetics and Lifecourse Epidemiology research cohort (EAGLE) using clinically defined data instead of self-reported data. This provided the opportunity to compare results of self-reported data to study results based on clinically defined data. The results from the studies were generally very consistent, highlighting many of the same genes and pathways.
"This coordinated approach to research significantly accelerates the replication and validation processes associated with solidifying new genetic discoveries," said David Hinds, Ph.D, 23andMe principal scientist.
"Through this collaborative effort, we have identified several genes that are responsible for a considerable proportion of allergy in the population," said Klaus Bønnelykke, MD, PhD and principal scientist from EAGLE. "This is an important step in allergy research."
1. Arbes Jr S Gergen P Elliot L Zeldin D (2005) Prevalences of positive skin test responses to 10 common allergens in the US population: results from the third National Health and Nutrition Examination Survey Journal of Allergy & Clinical Immunology 116:377-83