ROBERTSONIAN TRANSLOCATION

A type of chromosome rearrangement involving all of the essential genetic material of the long arms of two acrocentric chromosomes. The acrocentric chromosomes (those with the centromere near the end so there is only a tiny short arm) are chromosomes 13-15, 21 and 22 in humans. Named after W.R.B. Robertson who in 1916 first described this kind of chromosome rearrangement (in grasshoppers), Robertsonian translocations are also known as whole-arm or centric-fusion translocations. They are relatively common in humans and contribute to the toll of trisomy 13 syndrome and Down syndrome.