Blog | Tuesday, September 27, 2011

QD: News Every Day--Gene variants in asthma diminish steroid inhaler's efficacy

Scientists have honed in on the genetic variation that explains why some asthmatic patients don't benefit as much from steroid inhalers.

In a randomized, controlled trial, researchers followed 1,041 children being treated for asthma and their parents, choosing 422 white, non-Hispanic participants and their parents for genotyping. Of this group, 118 trios (a child and the two parents) were randomly assigned to treatment with budesonide (Pulmicort). Results appeared online Sept. 26 at the New England Journal of Medicine.

Investigators identified a variant in the glucocorticoid-induced transcript 1 gene (GLCCI1), rs37972, which was associated with a decrease in FEV1 in response to treatment with inhaled glucocorticoids.

An editorial noted that, "The clinical effect of the SNP [single-nucleotide polymorphism] is appreciable but not overwhelming." After treatment with inhaled glucocorticoids, participants who had two copies of rs37972 and rs37973 had a mean (±SE) increase in FEV1 of 3.2±1.6%, as compared with 9.4±1.1% for those with no copy of the variant. About 16% of the population will have two copies of the genotype responsible for the limited response to inhaled glucocorticoids.

The editorial pointed out that the next step must be clinical trials to determine whether knowledge of this information leads to better clinical outcomes. The author stated, "If personalized medicine is going to become a reality, we need to design and execute these critical trials."

The study was also presented at European Respiratory Society Congress in Amsterdam. In other news from the conference:
Maternal workplace exposure influences asthma. 42,696 children from the Danish National Birth Cohort were studied for the association between their mother’s occupation during pregnancy and asthma prevalence by age 7. The main focus of the study was on the effect of low molecular weight agents, such as synthetic chemicals and natural substances found in vehicle parts, furniture, shoe soles, paints, varnish, glues and wood-derived products. While 15.8% of the cohort had asthma, of the children whose mothers were occupationally exposed to low molecular weight substances, 18.6% had asthma.

Moderate alcohol use can diminish asthma.19,349 twins between the ages of 12 and 41 answered questionnaires over a period of 8 years to compare alcohol intake with the risk of developing asthma. Less than 4% of those who drank 1 to 6 units per week developed asthma. People who rarely or never drank had 1.4 times the risk, and heavy drinkers had 1.2 times the risk. Also, beer was associated with an increased risk of asthma when compared with no preference.

Belly fat associated with asthma. Researchers followed 23,245 adults without asthma, aged 19 to 55 years, for 11 years. Body-mass index was recorded with waist circumference to test overall obesity and central obesity, respectively. People who were centrally obese but not overall obese were 1.44 times more likely to develop asthma. People who were both centrally obese and obese overall were 1.81 times more likely to develop asthma.