there are many many threads on this topic on various parts of mn. if you do a search on mmr you will find that they are often very heated, with very strong views on both sides. Someone like jimjams would be best to point you in the direction of artacles that link mmr to autism, from what I've read on here though, the general view is:
mmr is predominantly safe. However, there are certain conditions that can be seen to trigger a bad reaction to mmr and thus could result in autism. If you have a history of cromes for instance in your family, or other bowel disorders, orif your ds has any other imunity disorders, then there is a higher risk of an adverse reaction to mmr. I believe, from what I've read, and have been told by someone who was involved in research for the World Health organization, that the main component for concern was the measles component, but that the reason it was the mmr that caused so much concern was because it has such a huge impact on the imune system which, if already compromised, would find it harder to cope with three vaxinations in one.
As I understand it, the general view is that 7% of all cases of autism have in some way been linked to mmr. This is a tiny percentage when you consider how many children are vaxinated each year.
Most of the parents on here who have autistic children are pro vaxination. There are some who are not, or whose own children have not been vaxinated because their children have conditions that are believed to be triggers for autism, but even those parents tend to be pro vaxination for children who are not perceived to be at risk.
Only you can make the ultimate decision, do some research, find out the actual facts and info re triggers, and make your decision based on that.
sorry for long post, and am sure that someone will be along to correct the bits I might have got wrong