Partial trisomy 13q21toqter de novo due to a recombinant chromosome rec(13)dup q.

A female is described who has a karyotype with an additional distal half of 13q in a recombinant rec(13)dup q chromosome. Since her parents have normal karyotypes, the origin of her karyotype is assumed to be a premeiotic pericentric inversion de novo with crossing-over within the inversion loop at meiosis. By means of various banding techniques, the breaks preceding the rearrangement could be located exactly. The joint between the duplicated segment and the satellites of the receptor chromosome is of special note. The phenotype of the patient stated at the age of 9 months and at the age of 7 1/2 years was found to be related to the segments involved in the partial trisomy. The clinical features were largely in accordance with previous case reports having an identical extent of the triplicated 13q segment.