Is autism from congenital disease or not?

We do not have the expertise to answer medical questions or contemplate questions like this. The best person you can ask this question would be an expert in autism. Maybe you could ask a faculty of medicine near your home residence, whether they can recommend you somebody.

You can find information about autism for instance in following books (which I found in our collections in Finland):

Wall, Kate, Autism and early years practise : a guide for early years professionals, teachers and parents. London : Paul Chapman Publishing, 2004.
Frith, Uta, Autism.: Esplaining the enigma. 1990.
Tinbergen, Niko, Autistic children.1985.
Tammet, Daniel, Born on a blue day : a memoir of Asperger's and an extraordinary mind. London : Hodder & Stoughton, 2006
Kendall, Philip C., Childhood disorders. Hove : Psychology Press, 2001
Luxford, Michael, Children with special needs. Edinburgh : Floris Books, 1994.
Nadesan, Majia Holmer, Constructing autism : unravelling the truth and understanding the social. London : Routledge / Taylor & Francis Group, 2005.

Here also information on the Internet:
http://www.nlm.nih.gov/medlineplus/autism.html