First trimester diagnosis of an unusual case of double aneuploidy with karyotype 48,XXY,+18 (Klinefelter-Edwards syndromes)

Objective: Double aneuploidy cases involving autosomal and sex chromosomes are very rare. Therefore, it is difficult to determine the clinical features and prognosis of these cases. In this case, a fetus with 48,XYY,+18 karyotype is presented. Case(s): Cystic hygroma, cleft lip and palate, and clubbed foot were detected in the prenatal ultrasonographic evaluation of a 31-year-old pregnant woman at 13 weeks of gestation. Chorionic villus sampling revealed double aneuploidy including Klinefelter and Edwards syndromes. The molecular result was consistent with the occurrence of nondisjunction error involving chromosome 18 in maternal meiosis I (mat MI) but the finding of the extra X chromosome could not be fully explained. Post-abortion fetal pathology specimen confirmed prenatal diagnosis. Conclusion: Double aneuploidy cases may rarely present with structural anomalies due to maternal meiosis error, without advanced maternal age, as in this case.