To quit or not to quit prenatal cytogenetic diagnosis?

Crolla, J.A. (2007) To quit or not to quit prenatal cytogenetic diagnosis? Chromosome Research, 15 (Supplement 1), 7-8. (doi:10.1007/s10577-007-1911-x).

Abstract

We have recently seen the development and use in
cytogenetic prenatal diagnosis of molecular techniques
for the rapid detection of numerical chromosome
abnormalities which comprise ~80Q of all
abnormalities detectable by karyotyping. Use of fluorescence
in situ hybridization (FISH) or quantitative
fluorescence polymerase chain reaction (QF-PCR)
makes it possible to detect the common aneuploidies
using uncultured amniotic fluid amniocytes (AF) or
chorionic villus samples (CVS) with results usually
available within 24Y48 hrs compared with the 7Y14
days needed to report a prenatal karyotype. In April
2007, the U.K._s National Screening Committee (a
Quango established by the Department of Health)
recommended that BQF-PCR alone (be offered) to
women of increased (screened) risk of Down_s syndrome,
but where the scan is normal (e.g. where a
nuchal translucency G 3mmis detected infirst trimester
screening). In this context QF-PCR should also be used
to test for + 13, + 18, in addition to + 21[. The NSC
continues to recommend QF-PCR and karyotyping in
cases of abnormal ultrasound scans and known parental
chromosome rearrangements. Funding for prenatal
karyotyping has already been replaced with QF-PCR
in two major English regions which serve populations
of several million. In this context, the U.K. Association
of Clinical Cytogeneticists (ACC) in 2005 published an
audit of 142,605 invasive prenatal diagnoses reported
from U.K. laboratories over 5 years. The karyotypes
were analysed by referral reasons and the results show
that QF-PCR replaces karyotyping, 1:100 (AF) and
1:40 (CVS) will have undetected abnormal karyotypes
and 1:300 (AF) and 1:100 (CVS) of these will be associated with a significant risk of an abnormal
phenotypic outcome. Despite these concerns, some
U.K. funding agencies have elected to quit karyotyping
in favour of QF-PCR. The possible implications for a
significant minority of patients will be discussed.

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