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Asthma development tied to genetic makeup, wheezing illness
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New data are shedding light on interactions between human rhinovirus wheezing illness and genes that may predispose children to asthma.
Carole Ober, PhD, Blum-Riese Professor of Human Genetics at the University of Chicago, and colleagues studied two cohorts of children from families at high risk for asthma. The children were followed from birth to 7 or 8 years of age.
All of the 200 children in the COAST cohort had at least one parent with asthma, respiratory allergies or both. The 297 Danish children in the COPSAC cohort were born to mothers with asthma. Both groups of children were evaluated for asthma from aged 6 to 8 years.
Minal Caliskan
Ober, along with Minal Caliskan, PhD, and others first investigated the links between genes and asthma in the COAST group, in which they found significant associations. Less than 30% of children in this group who lacked the asthma-related genetic marker were subsequently diagnosed with the disease vs. 40% of children with one at-risk copy and 50% with two. Children who had two copies of the asthma-related genetic variation also had far more human rhinovirus-related wheezing illnesses.
When the researchers combined both factors, the difference was striking. Only about 25% of children who had no wheezing illness from human rhinovirus developed asthma. About 40% of those who wheezed in the first 3 years of life but lacked the risk-related genes developed asthma. That increased to nearly 60% for those with one copy of the asthma-related allele and to 90% for those with two copies.
Next, they sought to replicate that finding in a similar group, but from a different continent. Although the overall asthma prevalence, based on slightly different criteria in the Danish cohort, was lower, the more-than-additive association between the at-risk genotype, wheezing illness in early life and asthma diagnosis persisted.
Exactly how the genes and viral infection interact to cause asthma is unclear. Two genes in the 17q21 region may play a role, the researchers said. About 90% of the children with these two copies of the common genetic variation and who wheezed when they caught a cold early in life went on to develop asthma by age 6 years, the researchers said.
“For the first time, we may have a genetic marker to identify which children who develop a wheezing illness when they have a cold in the first 3 years of life will be diagnosed with asthma later in childhood,” Ober and Caliskan told Infectious Diseases in Children.
Disclosure: Ober and Caliskan report no relevant financial disclosures.
Carole Ober, PhD, can be reached at the Department of Human Genetics, University of Chicago, 920 E. 58th St., Chicago, IL 60637; email: c-ober@genetics.uchicago.edu.
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