Rare and low frequency genetic mutations thought to explain missing heritability in asthma are unlikely to play a major role, scientists say. 

The researchers from the University of Chicago evaluated nearly 33,000 rare or low frequency genetic mutations in more than 11,000 individuals of a variety of ethnicities. They discovered that only mutations in three genes — GRASP, GSDMB and MTHFR — had a statistical link to asthma risk.

Previous studies have likely overestimated the heritability of asthma,” said study senior author Carole Ober, chair of the Department of Human Genetics at the University. “This could be because those estimates are based on correlations between family members that share environment as well as genes, which could inflate the heritability. Gene-environment interactions are not considered in these large scale association studies, and we know that these are particularly important in establishing individual risks for asthma.”