DLG4-related synaptopathy

DLG4-related synaptopathy is a condition that affects neurological development. This condition is characterized by delayed development and mild to moderate intellectual disabilities that typically becomes evident before age 2. Over time, many individuals with DLG4-related synaptopathy lose skills that they have learned, such as speech or motor skills. About 20 percent of people with this condition cannot speak. Affected individuals often have neurodevelopmental disorders, such as autism spectrum disorder or attention-deficit/hyperactivity disorder. About half of individuals with this condition have recurrent seizures (epilepsy) that typically begin in childhood. Brain changes can also occur. These include brain tissue loss (atrophy) and abnormalities of the tissue connecting the left and right halves of the brain (corpus callosum) or the  hippocampus, which is a region of the brain that is involved in learning and memory.

Individuals with DLG4-related synaptopathy can also have weak muscle tone (hyptonia), loose joints (joint laxity), or a spine that curves to the side (scoliosis). Movement problems, including impaired muscle coordination (ataxia), involuntary muscle coordination (dystonia), or rhythmic shaking (tremor) are common in people with this condition. Other problems can include migraine, sleep problems, or anxiety. Some people with DLG4-related synaptopathy have a distinctive body type that includes a long face, slim body, and long fingers.

Less commonly, DLG4-related synaptopathy can affect a person's vision. Affected individuals can have eyes that do not point in the same direction (strabismus), farsightedness (hyperopia), or involuntary movements of the eyes (nystagmus). Some affected individuals have blindness because the area of the brain responsible for processing vision is impaired. 

DLG4-related synaptopathy can also cause gastrointestinal difficulties that make it difficult to eat. These can include a backflow of stomach acids into the esophagus (gastroesophageal reflux disease or GERD).