25. Timothy Syndrome
Timothy syndrome is a genetic disorder that presents neurological and developmental defects and physical malformations. The most common symptoms include heart arrhythmias, webbing of the fingers and toes, and autism spectrum disorder, just to name a few. There is also atypical Timothy syndrome, which has similar symptoms except for the webbing of the fingers and toes.
Children with Timothy syndrome also tend to have small teeth with very poor enamel coating, making them prone to dental cavities that require teeth removal. Unfortunately, the average life span of children born with Timothy syndrome is roughly 2.5 years old, so there are no recorded adults alive with the syndrome.