Segregation analysis of a translocation (16;21)(p11;q22) in a large pedigree

A large family with an inherited reciprocal translocation (16;21) is described. An unbalanced karyotype due to adjacent-1 segregation was documented in 6 cases, whereas 25 children dying within the first year of life and 4 individuals dying at later ages probably had the same abnormality. Therefore minimal and maximal risk estimates were calculated to be 6.0% and 26.5% for female, respectively, 4.8% and 33.3% for male translocation heterozygotes. Among the karyotyped phenotypically normal offspring of male as well as female carriers the ratio of normal children to balanced carriers was not different from 1:1.