Introduction:
On May 18, 2013, the American Psychiatric Association introduced new diagnostic criteria, the so-called DSM-5, in which Asperger syndrome, autism, childhood disintegrative disorder, also known as Heller’s syndrome, and pervasive developmental disorders were classified as autism spectrum disorder (ASD). Based on the DSM-5 classification, Asperger syndrome can be described more specifically as ASD with specifiers, such as, for example, ‘without intellectual impairment’ and ‘without structural language impairment.’ The new classification assumes that typical symptoms, such as inflexible, stereotypical behavioral patterns do not necessarily have to appear in early childhood. The new standardizations limited falsely positive diagnoses; unfortunately, at the same time, reducing the specificity of diagnosis.

Aim:
The aim of this work, based on a systematic literature review, is to discuss various diagnostic procedures conducive to timely diagnosis of ASD.

Material and methods:
The source data were identified based on predefined primary medical headings: ASD, Asperger syndrome, and autism and the following keywords: diagnostic, epidemiology, genetic, prenatal, postnatal, DSM-5, and DSM-IV. The following databases were searched: PubMed, Google Scholar (searching using work titles) and UpToDate.

Results and discussion:
Proper anamnesis, good medical and parental care, and the application of adequate diagnostic procedures might be conducive to a much earlier diagnosis, approximately at the age of 2. Owing to parental perceptive observation as well as genetic and imaging examinations a group of children at a higher risk might be precisely identified, consequently facilitating a quicker diagnosis.

Conclusions:
Early diagnosis contributes to improved developmental outcomes.