Xq27.3q28 duplication syndrome

Xq27.3q28 duplication syndrome (also referred to as Xq27.3-q28 duplication syndrome or int22h1/int22h2-mediated Xq28 duplication syndrome in some contexts) is a rare chromosomal disorder caused by a duplication of genetic material on the long arm of the X chromosome, specifically in the region spanning bands q27.3 to q28. This region contains several genes important for neurodevelopment, and duplications in this area predominantly affect males, who carry only one X chromosome. Females who carry the duplication may be unaffected or mildly affected due to X-inactivation, though they can transmit the condition to their children. The syndrome primarily affects the central nervous system and is characterized by intellectual disability ranging from mild to severe, developmental delay (particularly in speech and language), and behavioral abnormalities that may include features of autism spectrum disorder. Additional clinical features can include facial dysmorphism (which may be subtle), hypotonia (low muscle tone), seizures, and recurrent infections in some cases. Growth abnormalities and feeding difficulties may also be present in early life. The severity and range of symptoms can vary depending on the exact size of the duplication and which genes are involved. There is currently no cure or specific targeted therapy for Xq27.3q28 duplication syndrome. Management is supportive and symptomatic, focusing on early intervention programs including speech therapy, occupational therapy, physical therapy, and behavioral support. Seizures, when present, are managed with standard antiepileptic medications. Regular developmental assessments and a multidisciplinary care approach are recommended to optimize outcomes for affected individuals.

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