Chromosome translocations in couples with multiple spontaneous abortions.

The reported incidence of balanced chromosomal translocations in couples with multiple spontaneous abortions (SABs) ranges from 0% of 31%. Because our experience has suggested that SABs are useful for ascertaining balanced translocations, we report the results of chromosome analyses performed on blood specimens from 440 individuals including 200 couples who were ascertained on the basis of two or more SABs. Balanced translocations were found in 3.6% of these 200 couples. For 122 of these couples, more detailed reproductive histories were available. For 48 couples with two SABs, four (8.4%) had balanced translocations; for 37 couples with three SABs, one (2.7%) had a balanced translocation; for 20 couples with four SABs, two (10%) had balanced translocations; and for 17 couples with five or more SABs, one (5.9%) had a balanced translocation. These 122 couples could also be classified on the basis of having abnormal or healthy children. For 40 couples with two or more SABs, one or more healthy children, and no abnormal offspring, two (5.0%) had balanced translocations; for 20 couples with two or more SABs and one or more abnormal children (and in some cases one or more healthy children), one (5.0%) had a balanced translocation; for 62 couples with two or more SABs and no other pregnancies, four (6.5%) had balanced translocations.