Dicentric (13;14) Karyotype

This karyotype is an example of a special type of translocation involving the entire long arms, and quite often the centromeres, of acrocentric chromosomes. It is called a Robertsonian Translocation. In this case the entire q, or long arm, plus centromere of a chromosome 13 has been fused with the entire q arm, plus centromere of a chromosome 14. This particular example is unbalanced and results in trisomy 13. There are two normal chromosome 13's plus the chromosome 13 involved with the translocation, thus there are three copies of chromosome 13. The translocation is shown as the right chromosome 14 in the karyotype. The karyotype is written as: 46,XY,+13,dic(13;14)(p11.2;p11.2). The key to the karyotype description is as follows:

46: the total number of chromosomes. The chromosome number remains 46 because the long arms of chromosomes 13 and 14 have basically fused into one chromosome.
XY: the sex chromosomes (male).
+13: indicates the presence of an extra chromosome 13.
dic(13;14): dicentric chromosome involving chromosomes 13 and 14. As with many Robertsonian translocations, the centromeres of both chromosomes are present, thus the "dicentric" designation.
(p11.2;p11.2): breakpoints in chromosomes 13 (p11.2), and 14 (p11.2) respectively.

The following ideogram gives a detailed illustration of this translocation.

Back to General Cytogenetics Information