Researchers at Ulm University in Germany have identified two promising blood-based biomarkers for Phelan-McDermid syndrome, including SHANK3 protein and beta-synuclein. In a pilot study of 23 individuals with Phelan-McDermid syndrome, lower SHANK3 levels and higher beta-synuclein levels were found compared to typically-developing controls. Individuals with Phelan-McDermid syndrome who had a history of regression had lower SHANK3 levels, and those with more significant language impairments had higher beta-synuclein levels. These findings also were observed in a Shank3 mouse model. Together, this suggests SHANK3 and beta-synuclein may be potential blood-based biomarkers in Phelan-McDermid syndrome. Although larger studies are needed to confirm the results, this research marks an important step toward identifying objective biological-based measures that may relate to disease severity and help monitor progression and evaluate treatment effectiveness.