A single gene variant is linked to an increased risk of several common diseases that involve inflammation, Swedish researchers say. The new study, published early online in the journal Nature Genetics, shows that a common version of the MHC2TA gene is associated with an increased risk of rheumatoid arthritis, multiple sclerosis (MS) and heart attack. The gene variant could be 'one of the single largest genetic causes of complex diseases with inflammatory components', according to author Fredrik Piehl, of the Karolinska Institute in Stockholm. The researchers say that other diseases could be linked to the gene, and that the discovery could lead to more reliable diagnostics and better treatments for patients.
The MHC2TA gene is responsible for 'switching on' other genes that make proteins crucial to the body's immune response, called major histocompatibility complex (MHC) molecules. Their job is to present bits of protein identified as 'non-self' to the body's T-cells - white blood cells that kill cells infected viruses. MHC molecules are thought to play a key role in autoimmune diseases such as MS, in which the body's immune system attacks its own tissues. The Swedish team first identified the rat version of the MHC2TA (MHC class II transactivator) gene, and then studied the role of its human counterpart in disease.
The researchers studied 387 heart attack patients, 548 patients with MS and 1,288 people with rheumatoid arthritis. They found that people who have had a heart attack are 39 per cent more likely to have a particular version of the MHC2TA gene, while those with arthritis are 29 per cent more likely have it. MS patients are 14 per cent more likely to have this version of the gene. The gene variant is common, present in around 20-25 per cent of the population. It appears to reduce the number of MHC molecules produced by the body. The findings suggest a new use for statins - usually taken to lower cholesterol levels - since such drugs appear to target the MHC2TA gene. When tested in MS patients, scientists found that statins produced an 'anti-inflammatory' effect.