Proximal Xq28 duplication syndrome

Proximal Xq28 duplication syndrome (also known as Xq28 duplication syndrome or int22h1/int22h2-mediated Xq28 duplication syndrome) is a rare X-linked chromosomal disorder caused by a recurrent duplication in the proximal portion of the Xq28 region of the X chromosome. This duplication typically encompasses several genes, and the clinical presentation predominantly affects males, while carrier females are usually asymptomatic or mildly affected. The condition primarily impacts the neurological system, with affected individuals commonly presenting with intellectual disability ranging from mild to severe, developmental delay (particularly speech and language delay), and behavioral abnormalities. Recurrent infections, especially respiratory infections, are frequently observed and are thought to be related to immune dysregulation. Key clinical features include hypotonia (low muscle tone) in infancy, seizures or epilepsy, feeding difficulties in early life, and distinctive facial features that may include a long face, prominent forehead, and midface hypoplasia. Growth abnormalities and gastrointestinal problems such as gastroesophageal reflux and constipation may also be present. Some patients develop spasticity in the lower limbs over time. The severity of symptoms can vary considerably among affected individuals, even within the same family. There is currently no cure or specific targeted therapy for proximal Xq28 duplication syndrome. Management is supportive and symptomatic, involving a multidisciplinary team approach. This may include physical therapy, occupational therapy, speech therapy, antiepileptic medications for seizure control, and proactive management of recurrent infections. Early intervention programs and individualized educational support are important components of care. Genetic counseling is recommended for affected families to understand recurrence risks and carrier status.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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