Ring chromosome
| Classification according to ICD-10 | |
|---|---|
| Q93.2 | Ring chromosomes and dicentric chromosomes |
| ICD-10 online (WHO version 2019) | |
A ring- shaped chromosome is called a ring chromosome , circular chromosome or chromosome ring . In prokaryotes that have only one nucleoid (bacterial chromosome), this usually has a circular shape. In mammals , however, it is a structural anomaly associated with the loss of chromosomal material.
anomaly
Ring chromosomes are formed when two breaks in the chromatids of a chromosome occur during cell division , so that the telomer sequences are lost. As a result, the ends of the linear chromosome can no longer be recognized as such by the DNA repair mechanisms. As a consequence, the break points can be connected so that they form a ring. If this ring tears during mitosis , chromosomal material can be lost ( deletion ).
In humans, ring chromosomes that lead to deletions lead to syndromes whose symptoms and course are different.
Examples are 18-R syndrome , ring chromosome 13 syndrome , ring chromosome 15 syndrome, and ring chromosome 20 syndrome .
Web links
- Ring chromosome 13 syndrome in an adult man with mild mental retardation (PDF file; 61 kB)
- Ring Chromosome 15 Syndrome in an Adult Woman (PDF file; 61 kB)
- Unique - The Rare Chromosome Disorder Support Group
Individual evidence
- ↑ Gholamali Tariverdian, Werner Buselmaier: Humangenetik . 3. Edition. Springer-Verlag, Berlin / Heidelberg 2013, ISBN 978-3-662-07817-4 , p. 148 ( limited preview in Google Book search).
- ↑ Walter Fröscher (Ed.): The epilepsies: Basics, clinic, treatment . 2nd Edition. Schattauer Verlag, Stuttgart [u. a.] 2004, ISBN 978-3-7945-2131-9 , pp. 42 ( limited preview in Google Book search).