Twenty five years ago, the University of the West Indies (UWI) Chronic Disease Research Centre (now called the George Alleyne Chronic Disease Research Centre) started a study aimed at isolating the genetic factors behind the high incidence of asthma in Barbados. A quarter of a century later, that study has reached some interesting conclusions that will help guide its next phase.
Deputy Principal of the Cave Hill Campus Professor Clive Landis told Health TODAY, “In the beginning, the Barbados Asthma Genetics Study was just a family study of genetics in Barbadian families, conducted by a Ph.D. student from Florida State University named Kathleen Barnes, who is now the Director of the Colorado Center for Personalized Medicine at the University of Colorado in Denver. Initially, we thought we would find only one or two genes for asthma, but it has turned out more complicated than that.”
Professor Barnes herself gave further insight into what the study had shown thus far. “So far we have surveyed about 2,000 people. Our initial focus was identifying asthmatics in pairs, including parents and extended families. We knew it was a complex disease and that many different genes contributed to its manifestation, but with the new technology that has emerged since 1993 when we began this survey, we can conclude that there are hundreds of thousands of genetic variants that contribute to asthma.”
The duration of the study has also enabled the researchers to trace the condition over more than one generation. Professor Barnes added, “In some cases, we can go back to an individual recruited as a child who is now an adult, and their asthma is no longer severe or they do not have asthma symptoms at all. There are also incidences where it may ‘skip’ a generation, so we are trying to figure out which aspects of their genetic makeup may cause that to happen.”
Statistician Michelle Daya noted that the incidence of asthma is higher in people of African descent; one of the main factors that governed the local study in the first instance. “Current developments in genetics make it easier for us to look at an area of your genome, subdivide the genetic makeup and see which part comes from which ancestor (European, African etc.) and this can help you narrow it down to see where exactly it came into the bloodline.”
The study also considered environmental factors that contributed to the condition, and Professor Barnes stated the local environment was unique in many ways. “We focused on common allergens like dust mites and roaches, which are a problem worldwide for asthmatics, but we found the concentration of these things was much higher than what was recorded elsewhere.
Now, this is not to say Barbadians do not keep their homes clean, but unlike other countries, Barbados’ tropical environment means we are exposed to these pests year-round. And in terms of exposure to exhaust emissions from vehicles, homes are closer to the road and there is a high volume of vehicular traffic in a small space.”
Andy Liu from the Children’s Hospital in Colorado, who only recently joined the research team, noted that there was a possibility that chemicals in processed foods could be a factor based on how they affected the genes. “This is becoming more of an interest area, because there may be simple things about diets that can affect our risk of having asthma. In the current study, we will be taking a closer look at how the genes are affected by these other mechanisms.”
Since Colorado was one of the first states in the USA to legalize marijuana smoking, and marijuana is claimed to be a cure for asthma, Liu said “We are doing studies on this, and thus far we have recognized that marijuana smoke can be just as dangerous as tobacco smoke as one of the environmental factors behind asthma. We are also embarking on studies relating to “vaping” and other new trends in smoking.”
Dr Harold Watson, who specialises in emergency medicine, noted that some 30% of the cases referred to the Accident and Emergency Department at the QEH were asthma-related, and the QEH was one of the few hospitals with a dedicated Asthma Bay catering to between 15 and 20 patients. He underscored the importance of the study in helping doctors treat patients in a more specialised fashion. “We thought we knew everything about asthma; we have all the medications, but based on the research we find some work differently depending on gene variants. So, from a clinical point of view, I can now tell my patients why they are not responding to certain medications, and it is not that the medicine is no good, but certain genetic factors may cause an adverse reaction in them. These studies will help us to move towards more personalised medication for asthma patients.”
Daya added that the researchers are presently seeking 300 more people, both asthmatics and non-asthmatics, to continue their studies of the condition. Interested Barbadians can contact Research Coordinators Pissamai Maul and Trevor Maul at 233-7949; 231-1338 and 426-6416.