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Robertsonian translocation (ROB) is a chromosomal abnormality where the entire long arms of two different chromosomes become fused to each other. It is the most common form of chromosomal translocation in humans, affecting 1 out of every 1,000 babies born. [ 1 ]
Chromosomal reciprocal translocation of the 4th and 20th chromosome. In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal, and Robertsonian translocation.
William Rees Brebner Robertson (31 May 1881 - 15 March 1941) was an American zoologist and early cytogeneticist who discovered the chromosomal rearrangement named in his honour, Robertsonian translocation, the most common structural chromosomal abnormalities seen in humans that result in syndromes of multiple malformations, including trisomy 13 Patau syndrome and trisomy 21 Down syndrome.
There are two main types of translocations: Reciprocal translocation: Segments from two different chromosomes have been exchanged. Robertsonian translocation: An entire chromosome has attached to another at the centromere - in humans, these only occur with chromosomes 13, 14, 15, 21, and 22.
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;21)] or itself [called an isochromosome, 45,XX,t(21;21)(q10;q10)] as seen in the translocation karyotype figure.
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).
Translocation may refer to: Chromosomal translocation, a chromosome abnormality caused by rearrangement of parts Robertsonian translocation, a chromosomal rearrangement in pairs 13, 14, 15, 21, and 22; Nonreciprocal translocation, transfer of genes from one chromosome to another; PEP group translocation, a method used by bacteria for sugar uptake
Such changes may involve several different classes of events, like deletions, duplications, inversions, and translocations. Usually, these events are caused by a breakage in the DNA double helices at two different locations, followed by a rejoining of the broken ends to produce a new chromosomal arrangement of genes , different from the gene ...