Interstitial deletion 2p accompanied by marker chromosome formation of the deleted segment resulting in a stable acentric marker chromosome.

We reexamined a moderately mentally retarded patient with mild dysmorphism previously described with de novo 47,XY, del(2)(p11;p21), +acefr. Using fluorescence in situ hybridization (FISH), we now confirm the chromosome 2 nature of the extra marker resulting from interstitial deletion of del(2)(p11;p21) as well the lack alpha satellite DNA pattern. The authors suggest that a reactivation process of a latent centromere may explain the origin of this stable extra marker.