Tetrasomy 5p syndrome

Tetrasomy 5p syndrome, also known as isochromosome 5p syndrome or supernumerary isochromosome 5p, is an extremely rare chromosomal disorder in which affected individuals carry four copies of the short arm (p) of chromosome 5 instead of the usual two. This extra genetic material is typically present as a supernumerary small marker chromosome composed of two copies of 5p joined together (an isochromosome). The condition arises as a de novo chromosomal abnormality and is usually detected prenatally or at birth. The syndrome affects multiple body systems. Key clinical features reported in the limited number of cases in the literature include intellectual disability, developmental delay, craniofacial dysmorphism (such as macrocephaly, frontal bossing, hypertelorism, low-set ears, and a broad or flat nasal bridge), muscular hypotonia, and skeletal anomalies. Some patients may also present with congenital heart defects, respiratory difficulties, and feeding problems in the neonatal period. Growth abnormalities, including both pre- and postnatal growth retardation or macrosomia, have been variably described. There is no specific cure or targeted therapy for tetrasomy 5p syndrome. Management is supportive and symptomatic, focusing on early intervention programs including physical therapy, occupational therapy, and speech therapy to address developmental delays. Cardiac, orthopedic, and other organ-specific complications are managed by the appropriate specialists. Genetic counseling is recommended for affected families, although recurrence risk is generally considered very low given the de novo nature of the chromosomal rearrangement.

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