What is the value of genetic testing in autism? What is the exome?

Why check an exome in children with autism and other neurologic illnesses?

This study reports molecular diagnostic yield from chromosomal microarray analysis and whole-exome sequencing performed for a population-based sample of 258 children diagnosed with autism spectrum disorder. 

The combined molecular diagnostic yield was

6.3% (95% CI, 1.7%-15.2%) in the essential group (4/64 children), 
28.6% (95% CI, 3.7%-71.0%) in the equivocal group (2/7 children), and 
37.5% (95% CI, 18.8%-59.4%) in the complex group (9/24 children; 3-group comparison, P = .001). 

The combined yield was significantly higher in the complex group when compared with the essential group (pairwise comparison, P = .002).

JAMA. 2015;314(9):895-903. doi:10.1001/jama.2015.10078.

What is the exome?