Objective: To report the first tertiary monosomy in a pregnancy loss to a female t(11;22) carrier.

Methods: The patient was a 34-year-old G10P1 female known to have a balanced translocation t(11;22)(q23;q11.2). She had one female livebirth (a translocation carrier) and eight miscarriages. Five female relatives known to be translocation carriers had a history of breast cancer, three of them premenopausally. The patient herself had a malignant melanoma.

Results: During the 10th pregnancy, ultrasound showed a viable embryo at 6 weeks of gestation, but loss of embryonic heartbeat by 7.5 weeks. Culture of the products of conception at 8 weeks of gestation showed the karyotype: 46,XY,+2,der(11)t(11;22)(q23;q11.2)mat,-22[4]/45,XY,der(11)t(11;22)(q23;q11.2)mat,-22[4], resulting from fertilization of the maternal 3:1 segregation product containing only the der(11) by a normal gamete. Subsequently, she became pregnant with a normal 46,XX fetus. FISH analysis indicated that the breakpoints on 11q and 22q in the patient were in the previously described region common to typical recurrent t(11;22). In addition, a nested-PCR-based approach showed that they were located within the same palindromic AT-rich sequence previously described.

Conclusion: This case demonstrates that the tertiary monosomy resulting from the 3:1 segregation is compatible with embryonic survival into the first trimester. It is also another example of apparent association of the constitutional translocation t(11;22) and breast cancer.