HUMAN RECIPROCAL TRANSLOCATIONS - IS THE UNBALANCED MODE AT BIRTH PREDICTABLE

Two methods of prediction for the risk of unbalance at birth were test ed on a large data base of reciprocal translocation (1376 families): t he pachyten diagram predictive method (PDPmethod) and the discriminant method (Dmethod). These method succeeded in correctly predicting the segregation mode in 66% of the data for the PDPmethod and in 80% of th e data for the Dmethod. The quality of chromosome material (in particu lar R bands) must be taken into account for more accurate prediction. Some difficulties still exist in predicting the 3:1 tertiary segregati on mode, which can frequently be incorrectly classified as the adjacen t 1 mode.