Autism spectrum disorder (ASD) is a neurodevelopmental condition with a significant genetic component influencing its diagnosis and management. This chapter describes the role of clinical genetic testing (CGT) in identifying molecular diagnoses within ASD, aiding in the accurate diagnosis and personalized interventions of individuals. It covers various CGT methods, such as karyotyping, chromosomal microarray analysis, and exome/genome sequencing, explaining their importance in identifying genetic variations contributing to ASD. The chapter also emphasizes the value of genetic counseling in providing comprehensive support to families undergoing CGT, ensuring they receive essential information about the genetic aspects of ASD and its implications. It also discusses the potential of pharmacogenetic testing in optimizing treatment plans for individuals with ASD, though its application is still emerging in clinical practice. Furthermore, the description of the future of CGT in enhancing personalized medicine for ASD points toward early intervention and tailored healthcare strategies as key benefits. Ethical considerations in genetic information, the impact of CGT on family dynamics, and the broader implications for personalized medicine in ASD care are also addressed. Overall, the chapter underscores the critical role of genetics in ASD and the integration of CGT into standard care practices to improve outcomes for affected individuals and their families.