Partial duplication/triplication of the short arm of chromosome 18 syndrome

Partial duplication or triplication of the short arm of chromosome 18 (18p) is a rare chromosomal anomaly in which part or all of the short arm of chromosome 18 is present in extra copies. This condition is also referred to as trisomy 18p or tetrasomy 18p depending on whether the region is duplicated (three copies) or triplicated (four copies). The extra genetic material from chromosome 18p leads to a variable clinical presentation that can affect multiple body systems, including the central nervous system, musculoskeletal system, and craniofacial structures. Key clinical features may include intellectual disability of variable severity, developmental delay, speech and language difficulties, distinctive facial features (such as a broad or flat nasal bridge, hypertelorism, low-set ears, and micrognathia), short stature, and muscular hypotonia. Some individuals may also present with congenital heart defects, skeletal anomalies, and seizures. The severity of the phenotype generally correlates with the size of the duplicated or triplicated segment and whether additional chromosomal imbalances are present. There is no specific cure for this condition. Management is supportive and multidisciplinary, focusing on the individual's specific symptoms. This may include early intervention programs, speech therapy, physical therapy, occupational therapy, and special educational support. Cardiac anomalies or other structural defects may require surgical intervention. Regular follow-up with a clinical geneticist and relevant specialists is recommended to monitor development and address emerging medical needs.

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