Types and Nonmenclature of Chromosome Abnormalities

Triploidy: 69, XXX; 69, XXY; 69, XYY

Three complete genomes per cell

Trisomy: 47, XXY; 47, XX; +21

Gain of an autosome is indicated by +

Monosomy: 45, X; 45, XY, -21

Loss of an autosome is indicated by -

Deletion: 46, XY, del(4)(p. 16.3)

Terminal deletion (breakpoint at 4p16.3)

Deletion: 46, XX, del (5) (q13q33)

Interstitial deletion of 5q13-q33

Inversion: 46, XY, inv(11) (p11p15)

Paracentric Inversion (breakpoints on the same arm)

Duplication: 46, XX, dup(1)(q22q25)

Duplication of region spanning 1q22 to 1q25

Insertion: 46, XX, ins (2)(p13q21q31)

A rearrangement of one copy of chromosome 2 by insertion of segment 2q21-q31 into a breakpoint at 2p13

Ring chromosome: 46, XY, r(7) (p22q36)

Joining of broken ends at 7p22 and 7p36 to form a ring

Marker: 47, XX, +mar

The cell contains an extra unidentified chromosome

Reciprocal Translocation: 46, XX, t(2;6)(q35;p21.3)

A balanced reciprocal translocation with breakpoints at 2q35 and 6p21.3

Robertsonian Translocation: 45, XY, der(14;21)(q10;q10)

A balanced carrier of of a 14;21 Robertsonian translocation. q10is not really a chromosome band, but indicates the centromere; der (derivative) is used when one chromosome from a translocation is present

Robertsonian Translocation (gives rise to one derivative chromosome): 46, XX, der (14;21)(q10;q10), +21

An individual with Down Syndrome possessing one normal chromosome 14, a Robertsonian 14;21 chromosome, and two normal copies of chromosome 21