Trisomy 18p syndrome

Trisomy 18p syndrome (also known as tetrasomy 18p when the extra material forms an isochromosome, or partial trisomy 18p) is a rare chromosomal disorder characterized by the presence of an extra copy of the short arm of chromosome 18. This additional genetic material disrupts normal development and affects multiple body systems. The condition may arise de novo or, less commonly, result from a parental balanced translocation or other chromosomal rearrangement. Key clinical features include intellectual disability of variable severity, developmental delay, short stature, and distinctive craniofacial features such as a round face, large or low-set ears, a broad or flat nasal bridge, strabismus, and microcephaly. Musculoskeletal abnormalities may include scoliosis, joint contractures, and limb anomalies. Some individuals may also present with congenital heart defects, seizures, and feeding difficulties during infancy. Hypotonia is frequently observed in the neonatal period, while behavioral difficulties and speech delays become more apparent during childhood. There is no specific cure for trisomy 18p syndrome. Management is supportive and multidisciplinary, focusing on the individual's specific symptoms. This may include early intervention programs, speech and physical therapy, special education services, cardiac evaluation and management if heart defects are present, and antiepileptic medications for seizures. Regular developmental assessments and follow-up with relevant specialists (cardiology, neurology, orthopedics) are recommended to optimize outcomes and quality of life.

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