Autism is a congenital disorder, meaning it is present from birth. Although the symptoms associated with autism generally are noticed during childhood, mild symptoms can result in a delay of the diagnosis for high-functioning autistic adults, states WebMD.
High-functioning autistic adults often can lead successful, independent lives and are generally of average to above-average intelligence, reports WebMD. Autism spectrum disorders cause a wide range of symptoms, including difficulty in social interactions resulting from a lack of empathy, inability to interpret nonverbal communication cues, and a tendency toward literal interpretation, which leads to the misunderstanding of humor and sarcasm. Approximately 10 percent of people with autism exhibit extraordinary talent in memorization, mathematics, art or music due to the disorder.