Doctors can now use a person’s genetic sequence as the basis for rational drug selection—a sign of how far personalized genomics has come in recent years. A case report published today in the New England Journal of Medicine illustrates the strength of this approach. The paper describes an extended Saudi Arabian family in which many young siblings suffered from a Parkinson’s-like condition affecting their movement. The children had normal levels of neurotransmitters dopamine and serotonin in their spinal fluid, suggesting they should have been healthy. The unique circumstances prompted researchers to use the latest advances in genomic sequencing to identify a mutation in the SLC18A2 gene, which encodes the protein vesicular monoamine transporter 2, or VMAT2, as the cause of the disease.