INTRODUCTIONWe aimed to develop and implement a short tandem repeat (STR) polymerase chain reaction alternative to fluorescence in situ hybridisation (FISH) for the preimplantation genetic diagnosis (PGD) of chromosomal translocations.

METHODSSelected informative STRs located on translocated arms of relevant chromosomes were used to discriminate between normal and unbalanced chromosome states in each embryo.

RESULTSPGD cycles were performed on five couples where one spouse carried a balanced translocation. 27 embryos were analysed, of which 12 were normal/balanced, 12 were abnormal/unbalanced and three were indeterminate. Four PGD cycles proceeded to embryo transfer, of which two led to pregnancy. The first pregnancy showed a normal male karyotype, and a healthy baby was delivered at term. A second pregnancy unexpectedly miscarried in the second trimester from unknown causes.

CONCLUSIONSTR analysis is a simple and suitable alternative to FISH for detecting unbalanced chromosomal states in preimplantation embryos.