Genetic risk in autism: new associations and clinical testing.

INTRODUCTION: Autism spectrum disorder (ASD) is prevalent in ∼ 1% of the population worldwide. It is also understood, through twin studies, that ASD has a heritability of 70 - 90%. Molecular genetic studies have presented some genetic risk factors associated with ASD that have potential implications in its diagnosis and genetic testing. AREAS COVERED: In this selective review, the author refers to previous systematic reviews that consecutively cited all the published papers on ASD at that time. The article presents the replicated genetic risk factors for ASD and the clinical relevance of these findings focusing on rare copy number variations and single gene mutations. The author provides the reader with a deeper insight into the complexity of ASD genetics and its implications for diagnostic genetic testing in ASD. The author also provides the reader with an algorithm for clinical genetic testing in individuals who are clinically diagnosed with ASD. EXPERT OPINION: Despite the high heritability of ASD and several replicated genetic risk factors, there is no clinical genetic test available that covers most genetic risk factors. Also, validity analyses on most available genetic testing procedures have not been performed so far. The variable risk genotypes, as well as related strongly variable phenotypes, have to be taken into account by genetic counseling.