Chromosome 5p duplication syndrome. 5p+ syndrome. Trisomy 5p syndrome.
Incidence
Rare syndrome. Duplication is usually due to unbalanced segregation of a parental autosomal translocation involving the short arm of chromosome 5 and another autosome and includes several duplications.
Clinical Characteristics
Chromosome 5, Trisomy 5p is a rare chromosomal disorder in which all or a portion of the short arm (p) of chromosome 5 (5p) appears three times (trisomy) rather than twice in cells of the body. Associated symptoms and findings may be variable, depending upon the specific length and location of the duplicated (trisomic) portion of chromosome 5p. However, in many affected infants and children, such abnormalities may include low muscle tone (hypotonia); occasionally an unusually small head (microcephaly) but usually large head and additional abnormalities of the head and facial (craniofacial) area; unusually long, slender fingers (arachnodactyly); delays in the acquisition of skills requiring the coordination of mental and physical activities (psychomotor retardation); and mental retardation. Duplication of the short arm of chromosome 5 most frequently associated with craniofacial, cardiac, renal, and limb abnormalities, and moderate to severe mental retardation. Dandy-Walker malformation (agenesis of the cerebellar vermis, hydrocephalus, and posterior fossa cyst continuous with the fourth ventricle) occurs in some cases. The phenotype is related to the amount of genetic material duplicated and the specific duplicated segment.
Precipitants
None
Provocation Tests
None
Diagnostic Procedures
Karyotype. Duplication of the short arm of chromosome 5.