The Principles of Clinical Cytogenetics - Extra Materials - Springer

34 Avirachan Tharapel
Fig. 5. Idiogram showing the G-banding pattern for normal human chromosomes at different band resolutions.
From left to right these are 300, 400, 550, 700, and 850 bands. (Reproduced from ISCN 2005 with permission
of S. Karger AG, Basel.)
always listed first. To designate an additional or a missing chromosome plus (+) and minus (–) signs
are placed before the specific chromosome number. Thus, –7,+18 would mean a missing chromosome
7 and an extra chromosome 18. Note that these abnormalities are presented in numerical order,
regardless of whether they involve gain or loss of a chromosome. A + sign can also be used to denote
additional copies of derivative chromosomes or accessory marker chromosomes, e.g., +der(6) or
+mar (see below).