asthma genes, namely on 17q21, and near the IL1RL1, TSLP, and IL33 genes in populations of European American, African American, and Latino descent. This indicates that variants of genes predisposing individuals to the development of asthma may be found distributed probably at varying prevalences in many different ethnicities but can also occur very specifically and uniquely in one particular ethnicity.
The researchers in this study belong to the EVE Consortium, which comprises nine groups of researchers who teamed up realising that finding new genes is becoming very difficult unless you pool data and join forces in oder to perform, for example, large genome-wide association studies (GWAS) studies that are sufficiently powered to also find rare predisposing genetic loci.
Study senior author Dr Carole Ober thinks that by this strategy, researchers have now have a really good handle on at least five genes that anyone would be comfortable saying are asthma risk loci, and that almost all of the genes other than PYHIN1 are trans-ethnic and important in all types of ethnic subgroups of patients.
The power of GWAS when you are looking for variants of complex diseases is only sufficient if you have data from thousands of participants, a logistical and financial challenge that is often beyond the resources of individual research teams. That is why more and more genetics studies using GWAS are the work of collaborating teams sharing resources as in this case by the members of the EVE Consortium.
Thus, for the study, the researchers pooled data from GWAS of asthma that altogether included 5,416 individuals with asthma who were of European American, African American or African Caribbean, and Latino ancestry, and replicated in another 12,649 individuals from the same ethnic groups. They found five variants or “susceptibility loci” (one on the 17q21 gene, and three near the genes IL1RL1, TSLP and IL33), that had previously been identified in a separate data set by the GABRIEL Study researchers who studied 40,000 European asthma cases, published in the NEJM.
Overall, these results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma, such as PYHIN1 genetic variants which are unique to individuals of African descent.