Hay fever could be a genetic condition in nearly one in ten people who have it, according to a huge study of 900,000 people – the largest ever on the allergy.
Known medically as allergic rhinitis, hay fever is the most common allergy on the planet and happens when the immune system reacts to plant pollen and dust.
It is not well understood why some people’s bodies develop the allergy but research has revealed 20 new genes which could be responsible for the condition.
Some of the genes change the DNA in the immune system which could be why they change how the body reacts to pollen.
The research almost doubles the number of genes known to be linked to hay fever, which scientists say could help improve treatments for the allergy.
It also claims that as many as 32 million people with hay fever worldwide could have their DNA to blame for their itchy eyes and runny nose.
Researchers have identified 20 new risk genes for hay fever and say eight per cent of people could have allergic rhinitis caused by their genetics
The research by the German Research Centre for Environmental Health and the University of Copenhagen looked at past studies of nearly a million people.
It is the largest ever study on hay fever, which is thought to affect 400 million people around the world and an increasing number in the West.
And the findings reveal that as many as eight per cent of cases – potentially 32 million people – are down to genetics.
As well as being caused by pollen, allergic rhinitis can also be triggered by the droppings of tiny house dust mites, and flakes of animal skin in the air.
The condition can give people a runny or blocked nose, red and watery eyes, and make them tired.
‘In order to treat hay fever we need to understand it better’
Dr Marie Standl from the research centre in Munich said: ‘In order to improve the prevention and treatment of this disease, we first need to understand why the body defends itself against certain, actually harmless substances.’
WHAT IS HAY FEVER?
Hay fever is an allergic reaction to pollen, a fine powder which comes from plants. There is more pollen in the air in the spring and summer when plants are flowering.
The reaction usually happens when pollen comes into contact with someone’s eyes, nose, mouth or throat.
Hay fever symptoms include coughing and sneezing; a runny or blocked nose; itchy, red or watery eyes; itching throat, nose, mouth or ears; headaches and tiredness.
People suffering from the allergy can put Vaseline around their nose to trap the pollen, wear wraparound sunglasses to keep pollen out of their eyes, wash clothes regularly and vacuum and dust indoors.
Avoiding grass, cut flowers and smoke can help reduce symptoms, as can drying clothes indoors where pollen is less likely to stick to them.
Source: NHS Choices
The team’s research studied differences in genetics between people with and without hay fever, and found 42 genes which increased the risk of the allergy.
In DNA people’s genes appear in different orders, which changes physical characteristics of their body and can make them more or less susceptible to certain diseases.
A total of 20 of the genetic differences linked to hay fever in the study had not been connected to the condition before.
Discovering these, the scientists say, brings them a step closer to understanding how people develop the condition and what can be done to stop it.
‘The genes only partly explain why so many people get the allergy’
‘The risk [genes] we have identified can help understanding the mechanisms causing allergic rhinitis and hopefully also to find targets for treatment and prevention,’ said Dr. Klaus Bønnelykke from the University of Copenhagen.
‘Still, the genes we identified only partly explain why so many people develop allergic rhinitis.
‘One important next step is to understand how risk genes interact with our environment.’
When researchers had identified the hay fever risk genes they tried to investigate what they each did – many were linked to the immune system and were involved in the process of white blood cells attaching to toxins in the body.
Scientists also noticed an overlap in the risk genes for hay fever and those for autoimmune diseases, for example rheumatoid arthritis or pulmonary fibrosis.
Their findings are published in the journal Nature Genetics.