Fragile X Syndrome is the most common known cause of autism worldwide. It can cause learning problems, intense anxiety, seizures, and more. There are also characteristic physical signs, such as large ears and a long face, but not everyone shows these signs. It tends to be more severe in boys than in girls.
A DNA test for Fragile X is widely available and very accurate. This blood test can detect carriers and fully-affected individuals. Any doctor can order the test. Unlike many genetic diseases, it may not be apparent that a person has Fragile X. It can be subtle or severe. Some girls have no signs at all.