Itchy and Scratchy Genetics

Some of us are just tastier, or at least to mosquitoes.

Just in time for summer, a new study of twins by researchers at the London School of Hygiene & Tropical Medicine, found that genetics may play a role in why some of us get bit more often by mosquitoes than others.

Beyond being the bane of summer evening barbeques, mosquitoes also spread deadly diseases like malaria and dengue fever. This kind of research could help in efforts to protect those most vulnerable, according to the researchers.

“By investigating the genetic mechanism behind attractiveness to biting insects such as mosquitoes we can move closer to using this knowledge for better ways of keeping us safe from bites and the diseases insects can spread through bites,” said coauthor James Logan, a medical entomologist at the London School of Hygiene & Tropical Medicine.

To test what makes two people more or less attractive to mosquitoes the researchers unleashed dozens of the bugs on both identical and non-identical twins.The researchers didn’t actually allow the mosquitoes to bite the participants, merely smell them. The researchers used something called a “Y-tube olfactometer,” which allowed mosquitoes to fly down one chamber or another in choosing between two people based on their body odor. The participants were also asked to avoid alcohol, garlic, and other strongly spiced foods for 24 hours prior to the test to ensure those strong smelling foods didn’t play a role.

The mosquitoes showed no preference in the case of identical twins – who are genetically identical. But in the case of the non-identical twins they clearly picked one twin over the other.

“Twins that were identical were very similar in their level of attractiveness to mosquitoes, and twins that were [not identical] were very different in their level of attractiveness,” Logan told National Public Radio.

The researchers concluded that the test suggested that there is a genetic trait for being “attractive” or “unattractive” to mosquitoes.This isn’t the first time scientists have delved into the realm of bug bite genetics.

Not long ago, researchers here at 23andMe looked at the genetics behind the different reactions people had to mosquito bites, finding an association between different genotypes on the SNP , which is on chromosome 4. People of European ancestry who are AA at that SNP are more likely to have larger bites. Those who are AC have average size bites, while those who are CC have smaller bites.

Overall about 41 percent of customers who’ve consented to research and responded to the survey said they get bit more often than others and 30 percent said when they were bit the bites were bigger and itched more than in other people.The focus of research on the pests could help stop the spread of disease.

“If we understand the genetic basis for variation between individuals it could be possible to develop better ways to control mosquitoes, and develop new ways to repel them,” said Logan. “In the future we may even be able to take a pill which will enhance the production of natural repellents by the body and ultimately replace skin lotions.”