The present invention relates to systems, devices, collections, techniques, and methods for diagnosing autism spectrum disorder (ASD) in a subject in addition to methods of treatment. In particular, the present disclosure relates to systems, devices, collections, techniques, and methods that utilize direct sequencing of micro ribonucleic acid (miRNA) or the use of miRNA probes having ribonucleotide sequences that may undergo nucleic acid hybridization with complementary nucleic acids present in a biological sample from the subject. Hybridization of the miRNA probes may be detected in the sample to determine if the subject has an ASD. Upon detection of an ASD using the methods discussed herein, therapy guidance may be effectuated to the subject.
