Identical chromosome imbalance in two siblings born to a mother with a double reciprocal translocation.

We report the case of a woman who carried two reciprocal translocations. Her karyotype was 46,XX,t(3;12)(q12;q21)(4;17)(p14;p13). She had two children, a phenotypically normal daughter (karyotype (46,XX,t(3;12)(q12;q21)) and a son with partial 4p trisomy (karyotype 46,XY,t(3;12) (q12;q21),-17,+maternal der(17)). She was pregnant with a female fetus who had the same karyotype as her son. She also reported a history of two spontaneous abortions. This viable recurrent abnormality was due to the maternal (4;17) translocation with meiotic segregation type 2:2 adjacent 1. In this case of the two reciprocal translocations carried by the mother, one led to imbalances, whereas the other remained balanced in the viable offspring.