Prenatal diagnosis of mosaic trisomy 2 associated with abnormal maternal serum screening, oligohydramnios, intrauterine growth restriction, ventricular septal defect, preaxial polydactyly, and facial dysmorphism.

OBJECTIVE

To present prenatal diagnosis of mosaic trisomy 2.

MATERIALS AND

METHODS

A 29-year-old woman underwent amniocentesis at 17 weeks of gestation because of abnormal maternal serum screening, and the cytogenetic result was 47,XY,+2[8]/46,XY[22]. She underwent repeated amniocentesis at 19 weeks of gestation. Interphase fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH), and quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on uncultured amniocytes. Ultrasound at 22 weeks of gestation revealed severe oligohydramnios, intrauterine growth restriction, and ventricular septal defect. The pregnancy was terminated at 22 weeks of gestation. Cytogenetic analysis was performed on parental blood, cultured amniocytes, cord blood, skin, liver, lung, umbilical cord, amnion, and placenta. aCGH analysis was performed on cord blood, skin, and liver.

RESULTS

In the samples of uncultured amniocytes, interphase FISH detected 11.1% (13/117) mosaicism for trisomy 2, aCGH analysis showed the result of arr [hg19] 2p25.3q37.3 (0-242,936,883)×2.46, and QF-PCR excluded uniparental disomy 2. QF-PCR on placenta revealed trisomy 2 derived from maternal meiosis I non-disjunction. Cytogenetic analysis revealed the following results: cultured amniocytes: 46,XY[21 colonies]; cord blood: 46,XY[40 cells]; skin: 46,XY[40 cells]; lung: 46,XY[40 cells]; liver: 47,XY,+2[4 cells]/46,XY[36 cells]; umbilical cord: 47,XY,+2[4 cells]/46,XY[36 cells]; amniotic membrane: 47,XY,+2[20 cells]/46,XY[20 cells]; and placenta: 47,XY,+2[40 cells]. The fetus postnatally manifested facial dysmorphism and preaxial polydactyly of the hand.

CONCLUSION

Interphase FISH and aCGH analyses on uncultured amniocytes are useful for rapid confirmation of low-level mosaic trisomy 2 at amniocentesis.