I'm wondering if the definition of aneuploidy includes loss of a chromosome arm (telosomy) or arms (ditelosomy).

I'm aware that aneuploidy normally depends on the number of discrete chromosomes (so a chromosome without an arm would be treated as one chromosome), but in the genetics course I'm taking, telosomy and ditelosomy were listed in 'types of aneuploidy'. Was this just for convenience, or does the definition include them?


1 Answer 1


To my knowledge aneuploidy regards to chromosome numerical change, not to losses within chromosomes. Take a look at this paragraph from An Introduction to Genetic Analysis. 7th edition (Griffiths AJF, Miller JH, Suzuki DT, et al. New York: W. H. Freeman; 2000.)

Aneuploidy is the second major category of chromosome mutations in which chromosome number is abnormal. An aneuploid is an individual organism whose chromosome number differs from the wild type by part of a chromosome set. Generally, the aneuploid chromosome set differs from wild type by only one or a small number of chromosomes. Aneuploids can have a chromosome number either greater or smaller than that of the wild type. Aneuploid nomenclature is based on the number of copies of the specific chromosome in the aneuploid state. For example, the aneuploid condition 2n − 1 is called monosomic (meaning “one chromosome”) because only one copy of some specific chromosome is present instead of the usual two found in its diploid progenitor. The aneuploid 2n + 1 is called trisomic,2n − 2 is nullisomic, and n + 1 is disomic.

This term (aneuploidy) was coined by Gunnar Täckholm in 1922, and if you want to check the original description you can just look for his original paper:

Täckholm, G. Zytologische Studien über die Gattung Rosa. Acta Hort. Berg. 7, 97–381 (in German) (1922).


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