Xq21 microdeletion syndrome

Xq21 microdeletion syndrome (also known as Xq21 deletion syndrome or choroideremia-deafness-obesity syndrome when associated with contiguous gene deletions) is a rare chromosomal disorder caused by a microdeletion on the long arm of the X chromosome at band q21. Because the deletion is on the X chromosome, males are predominantly and more severely affected, while carrier females may show milder or no symptoms depending on X-inactivation patterns. The clinical features of Xq21 microdeletion syndrome are variable and depend on the size and exact location of the deleted segment, as well as which genes are lost. Key features commonly include intellectual disability, sensorineural hearing loss (deafness), and choroideremia (a progressive degeneration of the choroid and retina leading to vision loss). Some patients may also present with obesity, behavioral difficulties, and other developmental anomalies. The syndrome can affect multiple body systems including the central nervous system, the auditory system, and the eyes. Additional features such as cleft lip and palate, agenesis of the corpus callosum, and skeletal anomalies have been reported in some cases. There is currently no cure for Xq21 microdeletion syndrome. Management is supportive and symptomatic, tailored to the individual's specific clinical manifestations. This may include hearing aids or cochlear implants for hearing loss, ophthalmologic monitoring and low-vision aids for choroideremia, speech and language therapy, special educational support for intellectual disability, and behavioral interventions. Genetic counseling is recommended for affected families to discuss recurrence risks and carrier testing.

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