The Alzheimers disease risk gene apolipoprotein E (ApoE) does not increase risk of MS
8th October, 2012
Since apolipoprotein E (ApoE) plays roles in regulating the immune system and repair mechanisms in the brain, variations in the (ApoE) gene were thought to be good candidate risk factors for MS. ApoE is the most important genetic risk factor for Alzheimers disease. The E4 variant of the ApoE gene increases the risk of Alzheimers while the E2 variant is thought to have a protective effect. A new large study has investigated whether the ApoE gene might also contribute to the risk of MS.
Recent large genetic studies have identified a large proportion of the genes that increase MS risk, however some genes are not well covered by the screening technologies – such as ApoE. This study used more traditional techniques and a computational method to determine which version of the gene people with MS were carrying compared to controls. Samples were taken from people with MS from several large international collaborations, including the ANZGene Consortium from Australia and New Zealand supported by MSRA.
Looking at over 13,000 MS genetic samples at two sites in the ApoE gene, the study found no evidence that that the E4 or E2 variants of ApoE were involved in risk of MS. Previous smaller studies have had confusing results, including one study published last week which showed a protective effect for the E2 variant in a smaller population. It is likely that the lack of association seen here is a true result since the study population is so large, giving the researchers additional statistical power to determine risk.
The scientists feel that this study ‘closes the case’ on the role of ApoE in MS risk. ‘The fact that previous studies yielded only inconclusive results can most likely be attributed to a lack in power, a problem overcome by the present analysis’, explained the authors, ‘even modest effects of the ApoE E4 and E2 variants on MS risk are unlikely’.