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Prenatal diagnosis, fetal pathology, and cytogenetic analysis of mosaic trisomy 14.

Authors
  • Cheung, S W
  • Kolacki, P L
  • Watson, M S
  • Crane, J P
Type
Published Article
Journal
Prenatal diagnosis
Publication Date
Nov 01, 1988
Volume
8
Issue
9
Pages
677–682
Identifiers
PMID: 3211857
Source
Medline
License
Unknown

Abstract

While true mosaicism occurs in only 0.25 per cent of genetic amniocenteses, nearly 2.5 per cent of amniotic fluid cell cultures contain a second cell line. In the common practice of prenatal diagnosis, an aberrant cell line confined to a single colony is usually disregarded. We present a case of mosaic trisomy 14 which was not detected on initial chromosome analysis. At birth, multiple malformations were apparent. Newborn cytogenetic studies revealed mosaicism [46,XX/46,XX,-14, +i(14q)] with an isochromosome 14 in 37 per cent of lymphocytes. Additional cells from the initial amniotic fluid culture were analysed post-delivery and the isochromosome 14 identified in only one of 12 total colonies. This case illustrates two important lessons in prenatal diagnosis. First, amniotic fluid cell cultures may not accurately reflect the relative distribution of the normal and abnormal cell lines within a mosaic fetus. Second, while it is generally reasonable to disregard mosaicism confined to a single colony, this policy will, on rare occasion, result in diagnostic error. This should be taken into consideration, particularly when dealing with autosomal trisomies potentially compatible with livebirth.

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