Choose and consent a genetic test after a normal microarray — OSCE

A 4-year-old boy is referred back to your general paediatric clinic with global developmental delay and mild dysmorphism. His chromosomal microarray, taken a year ago, is normal. Both parents attend and are willing to provide blood. The family has read about exome sequencing on the internet and want to know whether it is the next step, what it might find, and what happens if it finds something unrelated to the developmental delay. You are the paediatric registrar asked to decide on the next test, take consent, and answer the family's questions.