Risk of recurrence of fetal chromosomal aberrations: Analysis of trisomy 21, trisomy 18, trisomy 13, and 45,X in 1076 Japanese mothers

Objective: To evaluate the risk of recurrence of fetal chromosomal aberrations in women who had offspring with numeric chromosomal abnormalities. Subjects and Methods: This collaborative study consisted of 1076 Japanese women with a history of offspring with trisomy-21, -18, -13, or 45,X. Second-trimester amniocenteses were performed, resulting in 1248 fetal karyotypes that were analyzed with reference to prior offspring karyotypes and maternal age. Results: Of the 842 women with trisomy-21 offspring, 10 conceived another such fetus. In 2 women with 3 or more such offspring, parental mosaicism of trisomy-21 was suspected. The incidence of recurrence of trisomy-21 increased with age, and significantly exceeded the incidence of trisomy-21 fetuses in the general population. None of the 170 women with trisomy-18 offspring, and none of the 46 women with trisomy-13 offspring, had another such fetus. Of the 18 women with 45,X offspring, 1 with mos 45,X/46,XX had another such fetus. Conclusions: The risk of recurrence of trisomy-21 is affected by maternal age and parental germline mosaicism. The risk of recurrence of trisomy-18 or -13 appears to be much lower than that of trisomy-21. Women who give birth to more than 1 offspring with 45,X should be examined for mos 45,X/46,XX.