Rapid prenatal diagnosis of aneuploidies and zygosity in multiple pregnancies by amniocentesis with single insertion of the needle and quantitative fluorescent PCR.
OBJECTIVE
To investigate amniotic fluid (AF) samples retrieved in multiple pregnancies by single insertion of the needle, for rapid assessment of chromosome copy number, zygosity, and cross-contamination between fetuses, using Quantitative Fluorescent Polymerase Chain Reaction (QF-PCR) amplification of highly polymorphic microsatellite markers.


METHODS
Fifty-two multiple pregnancies were selected (47 twins, 5 triplets) and 108 samples of amniotic fluid were sampled between 12 to 20 weeks of gestation (mean 15.5) using the single-needle technique. Aneuploidy screening by QF-PCR amplification of short tandem repeats (STRs) on chromosomes X, Y, 21, 13, and 18 was carried out within 24 h of collection. Owing to the sampling procedure, the eventual presence of contamination between fetuses was also evaluated in every case.


RESULTS
Normal and aneuploid fetuses were readily identified by QF-PCR. Fetal reduction was made available, for trisomic fetuses, without further waiting for completion of fetal karyotyping. In twin gestations, the ultrasound examination of chorionicity was always in agreement with the molecular assessment of zygosity. Contamination between fetuses due to the sampling procedure with a single puncture was never observed.


CONCLUSIONS
Rapid prenatal diagnosis of aneuploidies by QF-PCR is a sensitive, efficient, and reliable assay. When applied in multiple pregnancies, it has the added value of allowing the assessment of zygosity in all cases, independently of chorionicity and fetal sex.
Cirigliano
Vincenzo
V
Department of Molecular Genetics, General Lab, Barcelona, Spain. vc@general-lab.com
Cañadas
Paz
P
Plaja
Alberto
A
Ordoñez
Elena
E
Mediano
Carmen
C
Sánchez
Angeles
A
Farrán
Inma
I
D000649:Amniocentesis / Q000379:methods*; D000782:Aneuploidy; D002882:Chromosomes, Human, Pair 13; D002887:Chromosomes, Human, Pair 18; D002891:Chromosomes, Human, Pair 21; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D019075:Electrophoresis, Capillary; D005260:Female; D005453:Fluorescence; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011272:Pregnancy, Multiple; D020080:Tandem Repeat Sequences; D014310:Triplets; D014427:Twins