Robertsonian
adjective
Rob·ert·so·ni·an
| \ ˌräb-ərt-ˈsō-nē-ən
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Medical Definition of Robertsonian
: relating to or being a reciprocal translocation that takes place between two acrocentric chromosomes and that yields one nonfunctional chromosome having two short arms and one functional chromosome having two long arms of which one arm is derived from each parent chromosome