Robertsonian Translocation

One-sentence definition. A Robertsonian translocation is a specific type of chromosome fusion where two acrocentric (short-armed) chromosomes join at their centromeres, producing a single metacentric chromosome and often a tiny fragment that is usually lost.

One-sentence analogy. A Robertsonian translocation is like pushing two T-shaped structures together at their bases — you get one large structure and a tiny fragment that falls away, reducing the chromosome count by approximately one.

Why it matters. Robertsonian translocations are the most common structural chromosome rearrangement in humans and many mammals. They cause Robertsonian carrier state in which individuals have 45 chromosomes yet are typically phenotypically normal. However, they increase risk of aneuploid offspring — particularly trisomy 21 (Down syndrome) or other trisomies — because the fused chromosome can malsegregate during meiosis. In the lab’s context, Robertsonian events are one mechanism of SA fusion and dysploidy, contributing to the negative correlation between Ne and chromosome fusion rates observed in Coleoptera and Carnivora.

Where you meet it in the wiki.

• Karyotype evolution overview — Robertsonian events as a common class of chromosomal rearrangement.
• Chromosome number evolution — Robertsonian translocations as a mode of descending dysploidy.

Primary citation. null

Prerequisites: chromosome fusion, autosome Next, learn about: chromosome fusion, dysploidy