First pregnancies after preconception diagnosis of translocations of maternal origin.

OBJECTIVE

To develop an approach to preimplantation diagnosis of translocations that would not require the use of specific DNA probes for each translocation type.

DESIGN

Retrospective analysis.

SETTING

Clinic.

PATIENT(S): Two patients with 45XX,der(13;14)(q10;q10) karyotypes and one patient with a 46XX,t(4;14)(p15;q24) karyotype.

INTERVENTION(S): Based on the observation that first polar body chromosomes remain at the metaphase stage for a few hours after oocyte retrieval, fluorescence in situ hybridization with chromosome-painting probes was used to perform preconception genetic diagnosis of translocation of maternal origin.

MAIN OUTCOME MEASURE(S): Oocyte FISH analysis.

RESULT(S): A total of 31 mature oocytes were produced, and results were obtained in 23 first polar bodies. After IVF-ET, all three patients became pregnant, preconception diagnoses being confirmed by prenatal diagnosis or birth.

CONCLUSION(S): Preconception diagnosis of translocations may reduce significantly the risk of chromosomally unbalanced offspring and pregnancy loss. This method is simpler than previous approaches because the need to develop specific DNA probes for each translocation type is avoided.