RECOMBINATION IN A BALANCED COMPLEX TRANSLOCATION OF A MOTHER LEADINGTO A BALANCED RECIPROCAL TRANSLOCATION IN THE CHILD - REVIEW OF 60 CASES OF BALANCED COMPLEX TRANSLOCATIONS

We report an unusual case of a balanced reciprocal translocation with a recombinant chromosome which has arisen from a familial balanced com plex translocation. Fluorescence in situ hybridization studies were es sential for the identification of the breakpoints. A review of 60 case s of balanced complex translocations (BCT) has revealed three cases si milar to ours. Carriers of BCT have a high risk of having spontaneous abortions or a child with an unbalanced karyotype. Certain types of ba lanced rearrangements involving an insertion can give rise to a simple r balanced translocation as a result of crossover. Our observations su pport the assumption that the chance that a de novo balanced complex t ranslocation is associated with an abnormal phenotype increases with t he number of breakpoints.