Nomenclature

Last revised in 1995, cytogenetic abnormalities are described by the ISCN (International System for Human Cytogenetic Nomenclature). Summary of the nomenclature used:

+ or - Gain or loss of chromosome following the symbol. p Short arm of chromosome. q Long arm of chromosome.

del Deletion. A deletion in the chromosome distal to breakpoint, or between two breakpoints if two are stated. der Derivative. A chromosome derived from a rearrangement.

Rearrangement (if known) is described. dic Dicentric. Chromosome has two centromeres derived from the two named chromosomes. dup Duplication. A segment of chromosome defined by two breakpoints is duplicated. i Isochromosome. Chromosome is composed of two identical arms rather than a p and q arm. ins Insertion. Segment from one chromosome is inserted into another.

inv Inversion. Segment of chromosome defined by two breakpoints is inverted compared to its normal orientation. t Translocation. Swapping of segments distal to the stated breakpoints in named chromosomes.

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