Repeated Pregnancies With Full Trisomy 21: A Case Report and Literature Review.

We report a rare case of a woman who had at least five pregnancies with full trisomy 21, despite being younger than 35 years. Chromosome testing was performed once on a newborn, three times on amniotic fluid, and three times on miscarriage samples. There were five cases of trisomy 21, one case of trisomy 16, and one case of a normal karyotype. Chromosome tests were performed on the patient and one of her partners to search for the cause, but they were found to be normal karyotypes. In addition, the patient and her parents' blood samples were collected and analyzed for whole-exome analysis (trio analysis), but the cause of the recurrent trisomy was unknown. The most likely cause of recurrent trisomy 21 was gonadal mosaicism in the patient.