Balanced Reciprocal Translocations Detected at Amniocentesis

Objective: To present perinatal findings, modes of ascertainment and parental decision in balanced reciprocal translocations detected at amniocentesis. Materials and Methods: Between January 1987 and August 2010, 82 cases with a simple reciprocal translocation, two cases with two separate simple reciprocal translocations and three cases with a complex chromosome rearrangement (CCR) were diagnosed by amniocentesis at Mackay Memorial Hospital, Taipei, Taiwan. The 87 cases originated from 76 families; 65 families with one case and 11 families with two cases. Results: In the 76 families, the main modes of ascertainment included advanced maternal age (n=38), a previous child with an unbalanced reciprocal translocation (n=11), recurrent miscarriage (n = 9), abnormal maternal serum screening results (n = 9), elective causes (n = 5), a previous child with congenital anomalies (n =2) and abnormal ultrasound findings (n = 2). In these families, there were 17 (22.4%) de novo cases including 14 simple translocations and three CCRs. Of 14 de novo cases with a simple translocation, one (7.1%) manifested a congenital malformation, which was related to an X-autosome translocation, and four (28.6%) were terminated. Of three de novo CCRs, two manifested congenital anomalies and one was terminated. In 87 cases, additional aneuploidy was noted in two cases including one inherited simple translocation with Turner syndrome, and one de novo CCR with concomitant deletions and duplication. Conclusion: Balanced reciprocal translocations detected at amniocentesis may be associated with fetal anomalies in cases of concomitant aneuploidy, de novo X-autosome translocation or de novo CCR. Genetic counseling of a de novo simple reciprocal translocation at amniocentesis remains difficult because approximately one-fourth of the parents opt for termination of the pregnancy, and detailed ultrasonography and array comparative genomic hybridization are helpful for parental counseling under such circumstances.