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A ring chromosome is an aberrant chromosome whose ends have fused together to form a ring. ... Ring chromosome 21: Short stature, microcephaly, reproductive abnormalities
Changes to chromosome 21 include a missing segment of the chromosome in each cell (partial monosomy 21) and a circular structure called ring chromosome 21. A ring chromosome occurs when both ends of a broken chromosome are reunited. Duplication in amyloid precursor protein (APP) locus (duplicated segment varies in length but includes APP) on ...
Ring chromosome 22, also known as ring 22, is a rare chromosomal disorder. ... Ring chromosomes 21 and 22 were first identified in 1970. At the time, ...
The extra chromosome 21 material may also occur due to a Robertsonian translocation in 2–4% of cases. [91] [101] In this translocation Down syndrome, the long arm of chromosome 21 is attached to another chromosome, often chromosome 14. [102] In a male affected with Down syndrome, it results in a karyotype of 46XY,t(14q21q).
Humans have five of these acrocentric chromosomes: 13, 14, 15, 21 and 22. When these chromosomes break at their centromeres, the two resulting long arms may fuse. The result is a single, large chromosome with a metacentric centromere. This form of rearrangement is a Robertsonian translocation. [citation needed]
Ring chromosome 14 syndrome is a very rare human chromosome abnormality. It occurs when one or both of the telomeres that mark the ends of chromosome 14 are lost, allowing the now uncapped ends to fuse together – thus forming a ring chromosome. It causes a number of serious health issues. [1] [3] [4]
Ring chromosome 20, ring-shaped chromosome 20 or r(20) syndrome is a rare human chromosome abnormality where the two arms of chromosome 20 fuse to form a ring chromosome. The syndrome is associated with epileptic seizures , behaviour disorders and intellectual disability.
Notice the three copies of 21q (two chromosomes 21 and the long arm of chromosome 21 fused to the short arm of a chromosome 14). The extra chromosome 21 material that causes Down syndrome may be due to a Robertsonian translocation. The long arm of chromosome 21 is attached to the long arm of another chromosome, often chromosome 14 [46,XX,t(14 ...