Is autism congenital？

Autism varies in characteristic and degree， happens in different races and economic classes， and will have influence on different groups of people. Autism is not caused by a single factor， but through the common influence of environmental factors， biological factors and genetic factors. Genetic factors， the study of twins and family members of autistic patients shows that some patients have significant genetic susceptibility. In addition， environmental factors are also easy to cause autism， heavy metals， pesticides， insecticides， additives， preservatives and other biological substances that are not normal in human body， while entering into the body， will cause harm. Some heavy metals， such as arsenic， lead， mercury， cadmium， antimony and manganese， can cause poisoning to the human nervous system.

（Answerer： Jia HUANG， Doctor of Medical School of Shanghai Jiao Tong University）

（From： Science China）