MISINTERPRETATION OF TRISOMY 18 AS A PSEUDOMOSAICISM AT THIRD-TRIMESTER AMNIOCENTESIS OF A CHILD WITH A MOSAIC 46,XY/47,XY,+3/48,XXY,+18 KARYOTYPE
✍ Scribed by C. M. A. VAN RAVENSWAAIJ-ARTS; J. H. A. M. TUERLINGS; A. F. J. VAN HEYST; J. G. NIJHUIS; J. NIEHOF; D. F. C. M. SMEETS
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 285 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0197-3851
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✦ Synopsis
False-negative trisomy 18 has been reported after chorionic villus sampling, but not after amniocentesis. We describe a double aneuploidy in cultured amniocytes that was initially misinterpreted as a pseudomosaicism. A patient was referred at 31 weeks of gestation because of fetal anomalies at ultrasound examination. Karyotyping of amniocytes showed a 47,XY,+3 karyotype in 61 clones and a 48,XXY,+18 karyotype in one clone. The latter was interpreted as a pseudomosaicism, the more since a second amniocentesis revealed only cells with a 47,XY,+3 karyotype. At 36 weeks gestational age, a boy was born with congenital anomalies suggestive of trisomy 18. A blood culture showed a 48,XXY,+18 karyotype, while in fibroblasts a 47,XY,+3/48,XXY,+18 mosaicism was found. Umbilical cord and bladder epithelial tissue also revealed normal 46,XY cells, besides the aneuploid cells. Therefore, the child proper had a 46,XY/47,XY,+3/48,XXY,+18 mosaicism with the clinical symptoms of trisomy 18. To the best of our knowledge, this is the first report of a false-negative result of trisomy 18 together with three sex chromosomes after amniocentesis. 1997 by John Wiley & Sons, Ltd.