Isochromosome 9p

Epidemiology and Etiology:

• Strong propensity for tissue-specific mosaicism
• Blood usually
• Lower frequency or absent:
• Skin
• Amniotic fluid
• CVS
• Resulting difficulty in prenatal diagnosis

Common sites:

Gross features:

• Ear malformations
• Cleft lip and palate
• Hypertelorism
• Bulbous/beaked nose
• Congenital heart disease
• Urogenital abnormalities
• Skeletal and joint problems
• Hypoplasia of digits and nails

Histologic features:

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• Percentage of abnormal cells in skin or other tissue may reflect prognosis better than that in blood

References:

· Lloveras E, Pérez C, Solé F, et al. Two cases of tetrasomy 9p syndrome with tissue limited mosaicism. Am J Med Genet A. 2004;124A(4):402-6.