A diagnosis of Smith-Kingsmore syndrome is confirmed by a combination of genetic testing that looks for changes in the MTOR gene, together with a clinical observation of the patient . This genetic testing is usually done with a blood or saliva sample, that undergoes whole exome sequencing (WES) or whole genome sequencing (WGS). If mosaicism (not all cells have a genetic change) is suspected, the genetic test may be performed on a different sample. The appropriate testing should be discussed with the care team.
Because SKS is a rare condition that many physicians are not familiar with, diagnosis can sometimes be challenging. Sometimes there is a change in the MTOR gene that is considered a “‘variant of uncertain significance”. This means that the genetic test alone cannot definitively show that the variant causes Smith-Kingsmore syndrome. In these cases, the care team will typically look at whether a person has other features in common with known SKS patients. Some will feel confident making a diagnosis even with a variant of uncertain significance; others may want to keep monitoring the patient over time.
As advances in genetics continue, we hope to see more precision in diagnosis.
~ Bernard Williams