FISH analysis in cell touch preparations and cytological specimens from formalin‐fixed fetal autopsies

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Abstract
Postmortem studies on still-borns and miscarriages are important to define the sex and eventually the morphologic anomalies correlated to chromosomal aberrations. When the conditions for carrying out a cytogenetic study do not exist, these chromosomal alterations can be investigated by nucleic acid fluorescent in situ hybridization (FISH), which can be performed on interphase nuclei, usually on formalin-fixed paraffin embedded tissues or on fresh cytological specimens. The objective of the present study is to prove whether this technique can be successfully applied to formalin-fixed cell touch preparations and cytological specimens obtained from foetal autopsies. The study was carried out 12 abortions some of which were spontaneous and some of which were therapeutic. The materials were formalin-fixed. Cell touch preparations and cytological specimens were obtained. The FISH was performed using X/Y probes (Vysis) and the Aneuvysion Kit (05J38-030, Vysis), the probes being for chromosomes 13/21 and X/Y/18. To verify the reliability of the technique, the same reactions were also performed on fresh analogous materials. The slides were evaluable, and the probes hybridized to interphase nuclei showed distinct signals. All the samples were adequate for FISH analysis without any notable difference in the results. Moreover, it is technically possible to perform this analysis not only on fresh but particularly on formalin-fixed cytological specimens. On the other hand, the use of this type of cytological samples, as compared to formalin-fixed and paraffin embedded tissue sections, has the advantage of presenting intact, noncut nuclei with preserved cytomorphology, avoiding the problems of overlapping nuclei and making the identification of the real chromosomal arrangement easier. Diagn. Cytopathol. 2008;36:633–636.