Proof of partial imbalances 6q and 11q due to maternal complex balanced translocation analyzed by microdissection of multicolor labeled chromosomes (FISH-MD) in a patient with Dandy-Walker variant

We report on a family in which a daughter is described with mental retardation, as well as malformations of the heart, and of the brain (Dandy-Walker variant). The patient's phenotype suggests a chromosomal rearrangement. However, her karyotype was unremarkable by conventional cytogenetic analysis. In order to detect chromosome rearrangements overseen by this method, the subtelomere regions of suspicious chromosomes were verified by fluorescence in situ hybridization (FISH). A rearranged derivative chromosome 6 was identified. Further examinations by FISH-microdissection (FISH-MD) revealed a maternal complex balanced translocation. The patient inherited the derivative chromosome 6 from her mother and therefore carries a partial monosomy 6q26-->qter and a partial trisomy 11q23.3-->qter.