The risk estimates for individual carriers of ten different familial r
eciprocal translocations detected among 500 couples with reproductive
failures are presented. These were established by application of the e
mpirical data analysed by Stengel-Rutkowski et al. (1988) and the guid
elines given in Stene & Stengel-Rutkowski (1988). Different risks were
estimated for unbalanced offspring at birth or at second trimester pr
enatal diagnosis for abortions, or stillbirths/early deaths. These ris
k estimates varied considerably from translocation to translocation. C
arriers of five translocations had risks for offspring with single-seg
ment imbalances. The birth risk figures ranged from 0.1% to 13.8%. Car
riers of five other translocations had risks for double-segment imbala
nces with birth risks ranging from 0% to 3.2%. The estimated risk figu
res were independent of the method of ascertainment. Among the parents
of the index cases we found nine maternal carriers and only one pater
nal carrier. This presentation illustrates the need for individual ris
k counselling of each carrier with reciprocal translocation regarding
further family planning.