Brunner Syndrome: A Potential Cause of Mild Intellectual Disability with Paroxysmal Behavioral Symptoms
Brunner syndrome is a rare, X-linked recessive neurodevelopmental disorder that should be considered when evaluating individuals—particularly males—with mild intellectual disability (ID) accompanied by episodic behavioral disturbances. This syndrome, caused by mutations in the MAOA gene, presents with a distinct constellation of cognitive and behavioral features, including impulsivity, aggression, and social difficulties, making early recognition crucial for effective intervention. Genetic Basis Brunner syndrome results from mutations in the monoamine oxidase A (MAOA) gene, which is located on the X chromosome. This gene encodes the enzyme monoamine oxidase A , responsible for breaking down neurotransmitters such as serotonin, dopamine, and norepinephrine. Loss of MAOA function leads to elevated levels of these neurotransmitters, which are believed to contribute to the behavioral and cognitive features observed in the syndrome. Because the disorder is X-linked, it primarily affec...