[Familial reciprocal translocations: estimation of the most probable imbalance in the offspring].

Four familial reciprocal translocations detected in a chromosomic study made to a population of newborn babies with two or more congenital defects following the methodology of ECEMC is analyzed. We followed the criteria of pachytene-dyagrem model of Jalbert et al (1980) to predict the most probable mode of imbalance for reciprocal translocations is followed. On the four translocations it was observed the type of segregation which was most probable following that model: three of them produced imbalance by a 3:1 segregation and the other one be adjacent 1. According to these results and regarding that a given translocation produces imbalances almost always by the same mechanism, we can provide a useful information for genetic counselling for these families.