15q11q13 microduplication syndrome

15q11-q13 microduplication syndrome (also known as Dup15q syndrome or chromosome 15q11.2-q13.1 duplication syndrome) is a clinically recognizable chromosomal disorder caused by the presence of at least one extra copy of the Prader-Willi/Angelman critical region (PWACR) on chromosome 15. The duplicated region contains several dosage-sensitive genes, including UBE3A and a cluster of GABAA receptor genes. The clinical significance and severity depend largely on the parent of origin, with maternally derived duplications being associated with a clinical phenotype, while paternally derived duplications are often clinically silent or associated with milder features. The syndrome primarily affects the central nervous system. Key clinical features include early-onset hypotonia, intellectual disability of variable severity, autism spectrum disorder or autistic features, speech and language delays, motor developmental delays, and seizures (including infantile spasms). Behavioral difficulties such as anxiety, emotional lability, and attention deficits are common. Some individuals may have mild dysmorphic features, though these are often subtle and nonspecific. The seizure disorder can be particularly challenging to manage and may become refractory to standard antiepileptic medications. There is currently no cure for 15q11-q13 microduplication syndrome. Management is supportive and symptom-based, involving early intervention programs, speech therapy, occupational therapy, physical therapy, behavioral therapy, and antiepileptic drugs for seizure control. Individuals with this condition benefit from a multidisciplinary care approach. The duplication can occur as an interstitial duplication (extra copy within the chromosome) or as an isodicentric chromosome 15 (idic(15)), with the latter typically resulting in tetrasomy of the region and a more severe phenotype.

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