Molecular investigation of the parental origin of a de novo unbalanced translocation 13/18.

We report a patient with a de novo translocation 13/18, identified by high-resolution banding. The breakpoints were ascertained by fluorescence in situ hybridisation with whole chromosome 13 and 18 paints. Short tandem repeat typing demonstrated the aberration to be of combined maternal/paternal origin and thereby confirmed its de novo and postzygotic formation. Thus, a gonadal mosaic in one of the parents resulting in a higher recurrence risk could be excluded.