Agree with stoppit as well. I would say it would be a concern only if there are cousin marriages generation after generation. Otherwise the stats are not much different 2% vs. 3%. Down syndrome has nothing to do with cousin marriage - but mothers age (more common as the women ages).
I agree people should take advantage of genetic counselling. My friend is from Yemen and she said in her family they do go for genetic counselling if they marry cousins.
Passionate - regardless of who you marry cousin or not if they are South Asian the kids WILL have higher risk of developing cardiovascular diseases and diabetes.