Your doctor may suspect FD based on your child's symptoms, your family's Ashkenazi heritage, and the results of your child's physical examination. Typical problems your doctor may find during an examination include a smooth, glossy tongue; decreased reflex response to tapping on a tendon; and the absence of overflow tears with crying.
To help confirm the diagnosis, your doctor may do histamine testing, in which a natural chemical called histamine is injected under your child's skin. Children who do not have FD will develop a small red skin bump called a wheal at the site of the histamine injection. Children with FD however, do not have the same reaction. If no wheal develops at the histamine site, your doctor may take a sample of your child's blood and send it for genetic testing to look for the mutated IKBKAP gene.