Why are women significantly more likely to contract an autoimmune disease than men? 

An autoimmune disease is a condition where the body’s immune system attacks healthy cells, resulting in illness. 

Speaking on his podcast, Show Me the Science with Luke O'Neill, the Trinity Professor said doctors have known for decades and women are disproportionately at risk of developping diseases such as rheumatoid arthritis, MS or lupus. 

“Tragically, it’s [an area of research that] been neglected and overlooked,” he said. 

“If it was the other way, if men were getting afflicted, we would have cracked it by now.” 

Despite this, Professor O’Neill said there is currently a “big focus” on this and scientists are starting to study the phenomenon. 

“Men get them as well, remember,” he said. 

“The insights we get from studying this sex difference in the susceptibility of these diseases can be pretty useful for both sexes. 

“It’s just a very interesting scientific topic.” 

Chromosomes

Professor O’Neill said the difference might be traced back to the different chromosomes that men and women have - generally, men have XY chromosomes and women have XX. 

“On the X chromosome, there’s about 1,000 genes - so, it’s quite heavy in terms of gene content,” Professor O’Neill said. 

“The Y chromosome only has about 70 - a lot less. 

“Now, if you’re female and you’re carrying two X chromosomes, the big question is you’re getting a double dose of genes and maybe it’s the double dose that’s causing the problem?” 

Some of these genes are known to be harmful in certain circumstances. 

“Two of them in particular - one of them is called TLR7 and another one called CD40L - if they’re overexpressed can cause inflammation and can cause harm,” Professor O’Neill said. 

“The notion then became, maybe women are expressing two doses of TLR7 or two doses of CD40L and that’s what’s driving their immune system into overdrive. 

“Guess what? That may be true, there’s evidence now that these are getting made in abundance and you’re getting a double whammy if you like and that double whammy might provoke disease.” 

Main image: Luke O'Neill in the Newstalk studio.