According to the American Speech-Language-Hearing Association, Autism is a neurodevelopmental condition characterized by atypical communication, social interaction and behaviors. People diagnosed with ASD may experience varying levels of functioning. Nonetheless, people diagnosed with ASD may experience social and behavioral challenges. To learn more about ASD and the screening/diagnosis process, go to the CDC website.
People with ASD are more likely to identify as asexual. Additionally, there appears to be more gender diversity among people with ASD. However, this does not mean that autistic people are uninterested in sex and/or relationships; Asexual people can have satisfying and fulfilling relationships and many autistic people experience a full range of sexual behaviors.
The National Autistic Society may be a UK charity, but it has a great section that shares a lot of relevant information on many subjects: