Autism also known as autism spectrum disorders (ASD) is etiologically and clinically heterogenous group of neurodevelopmental disabilities. ASD affects 1% of child’s population. The sex difference is observed with 4:1 male to female ratio. This is descriptive diagnosis based on observation and analysis of behavior and cognitive functions. ASD does not fit the criteria of known patterns of inheritance. For majority of patients polygenic model of inheritance with many interacting genes is the most probable. The etiology of ASD is poorly understood. It is estimated that a specific genetic etiology can be determined in up to 20% of individuals with ASD. Advances in microarray technology and next generation sequencing are revealing copy variant numbers (CNV) and single nucleotides polymorphisms (SNP) with important roles in synapse formation and function. For families where a specific etiology has been identified, the risk of recurrence in siblings generally depends on the etiologic diagnosis. For autism of unknown cause, the sibling risk varies across studies but is generally considered to range from 5 to 10 %.