Structural Abnormalities
Type Symbol Nature
Translocation t Two chromosomes break, rejoin, and exchange segments
Deletion del A segment of chromosome is lost
Inversion inv Two breaks occur; the middle piece is rotated and re-joins
Fragile site fra A chromosomal site with a tendency to break
Heterochromic site h
Chromosomal region that stains differently from the rest, often of variable size in the normal population
Duplication dup Duplication of a segment of chromosome
Ring r Arises from breaks in both arms, with loss of both ends to form a ring
Karyotype Nomenclature
46,XY, t(9;22)(q34;q11)Total number of chromosomes
Sex chromosome constitution
Sex chromosome constitution Description of abnormalities
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