A rare occurrence of trisomy 18 and trisomy 21 in a dizygotic twin pregnancy.

Objective: Case report of a rare combination of a trisomy 18 and 21 in a dizygotic twin pregnancy in a woman with a history of recurrent miscarriage, a neonatal death, no living offspring and Graves disease.
Methods: Case report and literature search.
Results: Only one other report in the literature of a combined trisomy 18 and 21 twin pregnancy was found.
Conclusion: The combination of a trisomy 18 and 21 in a dizygotic twin pregnancy is very rare. Despite the high frequency and clinical importance of aneuploidy, very little is known about the factors that may modulate meiotic non-disjunction.