UNBALANCED KARYOTYPE IN A HUMAN FOETUS DUE TO A RECURRENT FAMILIAL TRANSLOCATION

Couples with multiple miscarriages are at risk for carrying a balanced translocation since they may produce unbalanced gametes. Chromosomal imbalances may lead to spontaneous abortions, or an offspring with multiple congenital anomalies. This report emphasizes the importance of the cytogenetic investigations in couples with recurrent spontaneous abortions. A couple was referred for cytogenetic prenatal testing because of a history of recurrent miscarriages and due to the fact that after an ultrasound examination the foetal heart rate was not perceived and the suspicion that the pregnancy stopped growing was raised. Chromosome studies of the chorionic villi from the foetus revealed a karyotype with deletion of the terminal region of chromosome 11. Analysis of the chromosomes of the couple revealed the presence of a chromosomal rearrangement, a balanced translocation (10;11) for the mother, while the father had a normal karyotype. Further investigation of the family from the mother side revealed the same balanced translocation for her mother and her brother. Fluorescence in situ hybridization (FISH) using telomere probes for the short arm of chromosome 10 and the long arm of chromosome 11 was performed to better characterize the balanced state in the mother. This helped delineate the 46,XX,der(11)(11pter→11q21::10p14→10pter) karyotype of the foetus. This paper confirms that a chromosomal abnormality carried by one of the parents is likely to be associated with a high rate of spontaneous abortion. The diagnosis of the chromosomal balanced translocation of the genitors has significant implications for management and options in this family. Chorionic villi sampling should be offered to women who present with first-trimester spontaneous abortions and it is the most reliable method of determining the karyotype of spontaneously aborted foetuses.