Mangoes are related to poison ivy and contain a similar compound to urushiol, which is the toxin that causes allergic reaction to poison ivy. Some people are sensitive to the mango compound and will react to it just like poison ivy.
I learned today that the rate of autism has nearly doubled in the past 5 years; currently 1 out of 88 children is diagnosed with autism. In 2007 it was 1 in 160. But the upcoming new edition of the DSM may change the description of different parts of autism spectrum disorder - maybe lumping them together - and that could change the numbers too.