Genetics in autism diagnosis: adding molecular subtypes to neurobehavioral diagnoses.

Helen M. Johnson, John Gaitanis MD, and Eric M. Morrow, MD, PhD  introdUCtion: AUtisM genetiCs reseArCh hAs direCt relevAnCe to the CliniC Autism is a heterogeneous neurodevelopmental disorder that affects people of all races, ethnicities, and backgrounds and is about four times more prevalent in males. The incidence of autism has risen so dramatically over the past few decades that this increase has been termed the “autism epidemic.” A recent surveillance study reported a 57% average increase in the number of autism diagnoses in specified regions of the United States from 2002 to 2006, and estimated the current prevalence to be one in 110 children. The increase in diagnosis can be at least partly attributed to greater awareness, broader diagnostic criteria 6 and improved services for autistic children. Regardless, more children than ever are in need of proper diagnosis, treatment and services for autism. This article focuses on recent progress in genetic studies relevant to autism diagnosis. This progress has highlighted the genetic heterogeneity of autism, which mirrors the variation in clinical presentation of behavioral symptoms. Genetic research has recently revealed that about 10% of autism diagnoses can be subtyped according to genetic abnormalities. Genetic testing has, therefore, entered the clinical arena. As the multiple genetic etiologies of autism continue to be elucidated and as molecular genetic testing becomes more widely available and less expensive, genetic subtyping of autism will become more common.