A rare case of a false‐negative finding in both direct and culture of a chorionic villus sample

Abstract

A discrepancy is reported between the karyotype of both direct and cultured chorionic villus cells (46,XX) and a fetal skin biopsy (47,XX, +18). The significance of this result is discussed and compared with similar discordant findings reported in the literature.

The predictive value of findings of the common aneuploidies, trisomies 13, 18 and 21, and numerical sex chromosome abnormalities at CVS: experience from the ACC U.K. collaborative study

“…Of the 91 mosaic findings, no less than 17 showed complete discordance between the karyotypes of direct preparations and cultured cells ( Table 4 also includes the only entirely false-negative result, a trisomy 18 fetus with a normal result from both direct preparations and cultured cells, reported to the U.K. study (Pindar et al, 1992).…”

False-negative findings in chorionic villus sampling. An experimental approach and review of the literature

“…In contrast to the extensive literature data on chromosomal mosaicism in STC and LTC and its implication for false-positive findings, there are only few data on false-negative findings, mainly reported as single cases (Eichenbaum et al, 1986; Linton and Lilford, 1986;Martin et al, 1986;Simoni et al, 1987;Smidt-Jensen and Lind, 1987;Callen et al, 1988;Eiben et al, 1988;Leschot et al, 1988;Wirtz et al, 1988;Bartels et al, 1989;Hammer et al, 1991;Pindar et al, 1992). The false-negative fndings are almost always restricted to STC and for a long time no false-negative findings were known.…”

A 46,XX,der(13;14)(q10;q10),+21 child born after a 45,XX,der(13;14)(q10;q10) chromosomal finding in CVS

“…In three cases, the (semi)direct method was normal, the culture was non-mosaic abnormal, and chromosome studies of the blood (1997) of the child showed a mosaic sex-chromosomal abnormality. In the case reported by Pindar et al (1992), the (semi)direct as well as the culture method gave a false-negative result (46,XX), whereas the child had a 47,XX,+18 chromosomal pattern. By this new case it is again demonstrated that the most favourable technique for accurate prediction is the combination of the (semi)direct and culture method.…”

“…v a post-zygotic non-disjunction in the inner cell mass during embryogenesis (Crane and Cheung, 1988); v a twin pregnancy, with loss and re-absorption of the normal fetus; v a mosaic situation, undetected because of the low mitotic index; and v contamination of the villi with normal maternal cells (Pindar et al, 1992).…”