Genetic counselling of reciprocal translocations is quite difficult, as these balanced chromosomal rearrangements may produce both balanced and unbalanced gamets at meiosis. In this study, the proposed strategy for the identification of a prenatally determined balanced reciprocal translocation involving chromosomes 1q23 and 19q13.3 was discussed. Amniocenteses was performed because of advanced maternal age in the 17th week of gestation. First, the non-consenguinous parent who have a healthy living child, were offered to have their own karyotypes to determine the present rearrangement as familial or de novo. As we came across with the same translocation in the healthy mother, it was adressed as familial. The mother and the sister of her also had the same chromosomal rearrangement. The breakpoint of long arm of chromosome 1q23 was important as the fusion of this region with 19p13 could product a new chimeric gene in acute lymphoblastic leukemia. The parent were anxious about this information and the probable prognosis of pregnancy confused them. Based on the knowledge of only the one breakpoint region (1q23) share the homology with the chimeric gene formation, the parent decided to give birth to their fetus who had the general, 5-10%, risk of abnormalitity related to balanced familial rearragements.

Keywords: familial reciprocal translocation, malignansies, genetic counseling