Viking Genes Lead to Weak Lungs in Descendants

Proud of your Viking heritage? You’re likely to be more susceptible to lung conditions as a result of it.

According to a research study published by the Liverpool School of Tropical Medicine (LSTM), those of Viking descent may have a genetic predisposition to suffer from lung conditions such as emphysema, thanks to an adapted resistance to parasitic infections passed down from their ancestors. Archaeological digs from Danish Viking settlements, particularly from latrine pits from these communities, have revealed that Vikings suffered from high levels of gastrointestinal worms. Gene development within the Viking community led to adaptations to protect against parasitic disease, the researchers say, but these genetic adaptations have made contemporary humans with Viking blood more susceptible to lung disease as a result.

Pulmonary diseases like emphysema and chronic obstructive pulmonary disease (COPD) affect almost 5 percent of the population globally, which equates to more than 300 million individuals. There’s only one inherited risk factor for lung disease, a deficiency in alpha-1-antitrypsin (A1AT); a risk factor that is worsened by tobacco use. The role of A1AT is to protect the liver and lungs from proteases, enzymes that have a negative effect on lung tissue. Parasitic worms generate A1AT, but it is also produced by the human immune system – except in individuals of Scandinavian descent.

Why these genetic variants in modern human populations are so prevalent is somewhat of a mystery, especially as they evolved over a thousand years ago in Viking populations. According to Professor Richard Pleass of LSTM, the academic paper’s senior author, the proteases released by food contaminated with parasites would migrate to a number of different organs, including both the lungs and liver. The genetic variations in these populations led to the human body producing a form of A1AT that bound to immunoglobulin E (IgE), an antibody that evolved to provide additional protection from parasitic worms. Pleass added that these A1AT-bonded antibodies were much more resistant to the proteases released by the parasitic worms; this would have protected the Scandinavian populations of the day from the worms.

It’s only in the last hundred years or so that modern medical advances have been able to treat infections from parasitic worms, the professor remarked. With the need to protect the human body from these infections no longer relevant, these genetic variants of A1AT produced by those of Scandinavian descent no longer serve an evolutionary purpose. Moreover, these variants of A1AT now lead to a higher susceptibility to COPD, emphysema, and other lung diseases.

Founded in 1898, LSTM was the first institution of its kind to perform research, treatment and education concerning “tropical” medicine epidemics such as malaria, HIV/AIDS, dengue fever, and others. The recently published investigation was spearheaded by the Research Centre for Drugs & Diagnostics, LSTM’s arm for discovering, developing and delivering novel diagnostics and therapies for a wide variety of pathogens. The research study, which appears in the journal Scientific Reports, can be found online here.

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