Abstract
Chromosome abnormalities have long been recognized as an important cause of learning disabilities and multiple malformation syndromes. About 0.8% of live born infants have numerical or structural chromosomal anomalies that result in an abnormal phenotype. Identification of such anomalies is important clinically and also for accurate genetic counseling. Recently, molecular cytogenetic and array-based techniques have enabled higher resolution screens for chromosome anomalies. This brief review of the etiology of autism spectrum disorders (ASD) focuses on the heritable and non heritable risk factors that underlie this major neuro-developmental disorder. Since all patients with a chromosomal imbalance are dysmorphic, the association of ASD with a facial dysmorphism seems to be a good indication for chromosomal anomaly screening.