Reciprocal Translocation Carriers, Pre-implantation Diagnosis And Early Embryonic Chromosome Segregation

Objietives To investigate (l)the relationship between reciprocal translocation and spotaneous abortion; (2) the frequency of genetic imbalance embryo in reciprocal translocation carriers.Methods Karyorypes of 3936 patients with spotaneous abortion were analyzed using G-banding. Reciprocal translocation was diagnosised based on the international system for human cytogenetic nomenclature (ISCN 1995). Robertsonian translocation was not included. If two different cell line exit in same case, mosaic was diagnosed. The incidence of reciprocal translocations between different abortion numbers and different sex were calculated. Once patients were diagnosed with reciprocal translocations, genetic counseling was given and fertility risk was told. Those who want to try another pregnancy naturally were followed up till next pregnancy happened. If pregnancy continued to more than 16 weeks of gestational age, amniocentesis and karyotyping of fetus were done. The ratios of genetic balance and imbalance offsprings of translocation patients were calculated based on the total number of pregnancy , fetal loss and normal/balanced fetus or newborns.Results1. A total of 96 reciprocal translocation carriers were found among 3936 abortion patients (2.44%). The incidence of reciprocal translocation was 2.09% ( 47/2254) in patients with less than 3 times of fetal loss and 2.91% (49/1682) in patients with 3 or more than 3 times of abortion. No statistical difference was found. The incidence of reciprocal translocation in males and females was 1.33% (26/1956 ) and3.54% (70/1980) separately(P<0.01).2. All chromosomes except chromosome 17 and X took part in reciprocal translocations. The most frequently occurred translocated chromosomes were 5, 6, 7, 13, 14, 15 and 18.3. Among 40 patients who want to try another pregnancy naturally, 1 suffered from secondary infertility. Of 39 patients who got pregnancy, fetal loss happened in 27 cases. Amniocentesis and karyotype of fetus were done in 12 patients in whom pregnancy continued to more than 16 weeks of gestational age. Only one fetus had normal karyotype, all other fetuses were reciprocal translocations. 5 fetuses was born with normal phetype. 7 pregnancies is ongoing. There were 3 patients who had 1 healthy offspring separately before spontaneous abortions. The total number of pregnancy of 96 reciprocal translocation carriers was 296. The frequencies of genetic imbalance and balanced offsprings were 94.93%(281/296) and 5.07%(15/296) separately.Conclusions1. Reciprocal translocation is one of the most important causes of spontaneousabortion and has different influence on fertility capability between male and female.2. Non random chromosome break and recombinant occurs in patients withspontaneous abortions.3. The frequency of genetic imbalance offsprings of translocation carriers is veryhigh.