I am very interested in Autism. What can you tell me about this?
Well, in general, it's a developmental disorder usually characterized by difficulty with social interaction and communication.
At what age does this syndrome usually manifest? When do symptoms usually show themselves?
They say parents usually notice signs in the first two or three years of their child's life. There's no super-consistent pattern, as symptoms often develop gradually.
What type symptoms are usually seen in early childhood? 
Since it affects information processing in the way brain cells and their synapses connect, it might be delayed speech, hyper-sensitivity to external stimuli, inability/unwillingness to hole eye contact....a disconnectedness.
Is there any therapy or treatment that can be administered to minimize the effects of these symptoms?
There's no known cure -- but there have been cases of children who have recovered. The Magic Pill is a fascinating documentary that shows the impact of a keto diet on one young girl's autism. There are other speech and behavioral interventions, too.