Variant Chromosomes

16p

• C-bands
• Vary in size, position, and staining properties
• Position of centromere within heterochromatin of 1, 9, and 16 may vary
• Centromere duplication
• Y chromosome:
1. Virtual absence of heterochromatin
1. Y may appear to be only half the size of 22
2. Expansion of heterochromoatin
1. Y may appear to be the size of 13
3. Pericentric inversion
1. Metacentric appearance
4. Satellite on the end of the long arm
• Acrocentric short arms:
• Ag-NOR stain may be variable darkness
• Length
1. Short arm may appear to be absent
2. May be long enough to give appearance of a C group (or F-group 0
• Satellite size may vary
• Satellite number
• Translocations:
1. t(Y;15), t(Y;22)
1. C-band material from the long arm of the Y is translocated into the short arm of an acrocentric
• Euchromatic variants:
• Have been reported for 1, 5, 8, 9, 15, and 16:
1. 8p23.1
2. 9p12
3. 15q11.2