Segregation analysis of four translocations, t(2;18), t(3;15), t(5;7), and t(10;12), by sperm chromosome studies and a review of the literature.

We examined the meiotic segregation patterns of 444 sperm cells belonging to four reciprocal translocation carriers, t(2;18)(p21;q11.2), t(3;15)(q26.2; q26.1), t(5;7)(q13; p15.1), and t(10;12)(q26.1;p13.3). For the t(2;18) carrier, the frequencies of alternate, adjacent-1, adjacent-2, and 3:1 segregations were 41.9%, 35.2%, 14.4%, and 8.4%, respectively. For the t(3;15) carrier, the segregation pattern was 48% alternate, 36% adjacent-1, 12% adjacent-2, 2% 3:1, and 2% 4:0. One cell was the result of a 4:0 segregation. For the t(5;7) heterozygote, the corresponding segregation frequencies were 40.2%, 26.2%, 16.6%, and 17.0%. This translocation heterozygote showed a higher number of 3:1 segregations than adjacent-2 segregations, which is unusual. The t(10;12) segregations were 61.1%, 26.3%, 6.9%, and 5.6%. The percentages of chromosome abnormalities unrelated to the translocation ranged from 0% to 0.6% for aneuploidy and from 5.5% to 10.9% for structural abnormalities. These frequencies are within the ranges for control donors. Sperm chromosome data from the literature on the segregation of 30 reciprocal translocations were reviewed.