Cri-du-Chat Syndrome (CdCS) is a rare genetic disorder caused by missing pieces (deletions) of chromosome 5. This study compared 3D facial photos of 29 individuals with CdCS and thousands of unaffected individuals to understand how different deletions affect facial features. Large deletions caused consistent features like a short space between the nose and upper lip, wide-set eyes, and a prominent nasal bridge, but with varying intensity. Smaller deletions caused different and more variable facial changes. The study shows that 3D facial analysis can provide an objective and detailed assessment of facial shape that is complementary to a doctor’s clinical evaluation. (By Dr. Michiel Vanneste, https://jmg.bmj.com/content/early/2025/11/20/jmg-2025-110940 )