This supernumerary ring 20 can cause multiple anomalies but no epilepsy, and this resulting syndrome should be differentiated from ring chromosome 20 syndrome.
12.
CGH is only able to detect unbalanced inversions or ring chromosomes do not affect copy number, which is what is detected by CGH technologies.
13.
A similar association between a ring chromosome and an autosomal-dominant disease has been reported for ring 17 chromosome and Miller-Dieker syndrome.
14.
Although not discussed explicitly in relation to neocentromeres, it is worth noting that the breakage-fusion-bridge cycle involves ring chromosomes too.
15.
Complex rearrangements, including segmental microdeletions and microduplications, have been seen in numerous ring chromosomes, providing important clues regarding the mechanisms of their formation.
16.
Ring chromosomes were discovered from their unusual frequencies of recombination in an attached-X stock, which revealed a circularized X-chromosome upon cytological examination.
17.
Since chromosomal analysis or karyotype testing is not a routine investigation for patients with epilepsy, the diagnosis of ring chromosome 20 syndrome is typically delayed or unrecognized.
18.
In most individuals with ring chromosome 20 syndrome, a certain percentage have two normal chromosome 20s and the remainder have one normal and one ring 20 chromosome.
19.
If it occurs during embryonic growth the ring chromosome may be present in only some of a person's cells ( i . e . Mosaicism ).
20.
Perhaps further studying of ring chromosomes and diseases, from the perspective of neocentromere formation, may shed light on mechanisms of tumor formation due to chromosome abnormalities.
