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Admixture mapping effectively identified asthma susceptibility in Latino populations

The 6q15 and 8q12 chromosome regions may be asthma triggers, and case-control admixture mapping is an effective tool for performing genome-wide association studies in Mexican and Puerto Rican populations, according to study results.

The study evaluated Mexican and Puerto Rican participants, aged 8 to 40 years, who had been diagnosed with mild or moderate-to-severe asthma in an attempt to identify unique genetic locations responsible for those individuals being more susceptible to asthma. All participants’ parents, and maternal and paternal grandparents were required to self-identify as either Mexican or Puerto Rican.

Although Mexicans and Puerto Ricans typically fall under the umbrella term “Latino,” Puerto Ricans living in the United States have the highest asthma incidence, morbidity, and mortality. Mexicans living in the United States have the lowest.

The participants were divided into an asthma group (n=529) and a control group (n=347), with 253 Mexicans and 276 Puerto Ricans having asthma. The control group was composed of 158 Mexicans and 189 Puerto Ricans.

Utilizing a program called ADMIXTURE, the investigators evaluated the participants’ genomic levels for European, Native American, and African ancestry. Admixture mapping compared the genetic ancestry variable between cases and control participants at a given location in the genome. It was employed on both the asthma and control groups to compare the relative percentages of European, Native American, and African ancestry.

Results indicated that there were 62 admixture mapping peaks between the Mexican and Puerto Rican populations (P<10^–3) “that were significantly enriched for previously identified asthma-associated genes (P=.0051),” researchers said.

The investigators noted that the 6q15 chromosome was significantly associated with asthma in the Mexican participants, but not in the Puerto Rican participants.

Mexican and Puerto Rican participants showed an asthma association with African and Native American ancestry, respectively, at chromosome 8q12.1. The investigators considered this nominally significant, however.

“Case-control admixture mapping … might be useful for identifying regions that contribute to both shared and population-specific differences in asthma susceptibility,” researchers concluded.

Disclosure: See the study for a full list of relevant disclosures.