Partial duplication/triplication of the short arm of chromosome 5 syndrome

Partial duplication or triplication of the short arm of chromosome 5 (5p) syndrome (Orphanet code 262725) is a rare chromosomal anomaly in which a segment of the short arm of chromosome 5 is present in extra copies — either duplicated (trisomy for that region) or triplicated (tetrasomy). This condition is also referred to as partial trisomy 5p or partial tetrasomy 5p, depending on the extent of the extra genetic material. The clinical presentation is variable and depends on the size and precise location of the duplicated or triplicated segment, but commonly reported features include intellectual disability, developmental delay, craniofacial dysmorphism (such as macrocephaly, frontal bossing, hypertelorism, a broad or flat nasal bridge, and low-set ears), and growth abnormalities. Some patients may also present with congenital heart defects, seizures, and musculoskeletal anomalies. The condition can arise de novo or be inherited from a parent carrying a balanced chromosomal rearrangement such as a translocation or inversion. When a parent carries a balanced rearrangement, there is a recurrent risk for future pregnancies. Diagnosis is typically made through karyotyping, fluorescence in situ hybridization (FISH), or chromosomal microarray analysis, which can precisely define the breakpoints and extent of the duplicated or triplicated region. Genotype-phenotype correlations remain challenging because of the variability in segment size and gene content involved. There is currently no curative treatment for partial duplication or triplication of 5p. Management is supportive and multidisciplinary, focusing on early intervention programs for developmental delay, speech and occupational therapy, management of seizures if present, cardiac evaluation and treatment for congenital heart defects, and regular monitoring of growth and development. Genetic counseling is recommended for affected families to assess recurrence risk and guide reproductive planning.

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