Reproductive risk of t(13q14q) carriers: case report and review.

We report a four-generation kindred with a balanced 13q14q Robertsonian translocation. The proband had the Down sydrome, due to trisomy of chromosome 21; he also carried the balanced D-group translocation. S segregation analysis of 86 sibships was performed to examine the risk of t(13q14q) carrier parents having trisomy 21, 47,XXY, or trisomy 13 children by which a number of families were ascertained. None of these disorders recurred after birth of the propositi. The frequency of abortions was not different from that of the general population. The conditional segregation ratio for balanced translocation carriers among the phenotypically normal offspring of carrier parents was 0.55 +/- 0.04.