Immune System and Parkinson’s Disease – Is there a link?

November 12, 2012

Immune System and Parkinson’s Disease – Is there a link?

A study undertaken by researchers from the New York State Department of Health and several other academic and medical centres in the USA has led the BBC to state that, “The immune system may have a key role in the development of Parkinson’s disease,” The National Institute of Neurological Disorders and Stroke funded the study aided by several American organisations. The study was published in Nature Genetics which is known topublish the highest quality research into geneticsand is a peer reviewed medical journal. The BBC went on to speculate that a link between Parkinson’s disease and the genes associated with controlling immunity had been found.

The study was a genome-wide association study which is the type commonly used when genetic comparisons have to be made, for example to identify if there are any genetic similarities between a healthy sample and one with a disease. In this case it seems that the researchers identified that genetic variants usually associated with the immune system were found in the DNA of Parkinson’s disease sufferers. This research has identified that a region related to the immune system also has an association with Parkinson’s disease. The study had samples from 2,000 Parkinson’s disease sufferers and compared the DNA against a healthy group.

What did the research involve?

The study selected 2,000 people with Parkinson’s disease from around the Oregon, Washington, Georgia and New York areas. The control group, that’s people without Parkinson’s, was chosen from the same geographical areas with the aim of being able to compare like with like. That group numbered 1,986 people. The groups were also adjusted in the analyses to allow for difference in age, gender and Jewish and European ancestry.

DNA samples from both groups were taken the identify differences between those with Parkinson’s and those who have no disease. If any variants were found between the groups additional testing would be carried out in independent samples with the aim of reproducing the same result. Once the results were completed the researchers discussed any associations identified between the genetic variants and whether the reasons for these associations were known or expected.

The group of healthy participants were on average 12 years older than those with Parkinson’s. The researchers say that this strengthens the study because it decreases the chance that the people were too young to contract the disease.

What were the results?

Associations between Parkinson’s disease and two genetic areas already known to exist were identified. The two areas are known as SNCA and MAPT. However a part of the genome employed in the production of proteins known to help the immune system recognise and fight off bacteria and viruses was also seen. This new variant is known as ‘rs3129882’ and resides in the genetic area HLA, on chromosome 6.

The researchers believe that their findings ‘offer new targets for drug development’. This is because the study has confirmed a new association in addition to confirming known links between single letter variations of the genetic code between healthy samples and samples from Parkinson’s sufferers. Now researchers know that some of the immune system’s genetics are associated with Parkinson’s disease it allows for drugs to be manufactured which more accurately target the area under investigation.

Conclusion

Because of this study further knowledge has been gained in the field of genetics and Parkinson’s disease. Even though the association between Parkinson’s disease and the immune system will only have a ‘modest effect on Parkinson’s disease risk’ it adds to the sum of knowledge amongst experts involved in the work.

The association identified was in a non-coding region of the genetic code. This tells us that it is not a protein producer, but has a bearing on the genetic code in a different manner. The pool of knowledge relating to Parkinson’s disease now knows that there are four major regions associated with the disease. It’s also been discovered that people who have four of the variants have about double the risk for Parkinson’s compared to those without any variants. At this point it should be stated that the risk of developing Parkinson’s disease is minimal and even when all four variants are present it does not guarantee that the disease will develop.

Dr Kieran Breen, director of research at Parkinson’s UK, reinforces the need for collaboration in this field of work, saying “This research, combined with Parkinson’s UK funded research at Oxford University into the role of inflammation, may lead to the development of new drug treatments for the condition.”

The results of this study may add to treatments or improved diagnosis of Parkinson’s, but it is too early to predict the full implications of these findings. This study has identified that the region affected is only associated with a slight effect on the risk of Parkinson’s disease developing. However when considered with other research, the increasing effect of this new association with others previously known about is thought to be significant.

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