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2009 Vienna - European Society of Human Genetics

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Prenatal and perinatal genetics<br />

P05.53<br />

Rapid prenatal <strong>of</strong> chromosome aneuploidy by Qt-PcR<br />

J. Kasnauskiene1,2 , N. Krasovskaja2 , V. Kučinskas1,2 ;<br />

1 2 Vilnius University, Vilnius, Lithuania, Vilnius University Hospital Santariskiu<br />

Clinics, Vilnius, Lithuania.<br />

QT-PCR can detect the great majority <strong>of</strong> chromosome abnormalities in<br />

prenatal samples being targeted to chromosomes 13, 18, 21 X and Y.<br />

It is a rapid robust and accurate test for the prenatal diagnosis <strong>of</strong> most<br />

frequent trisomies. Main advantages <strong>of</strong> the test: low cost, speed and<br />

automation large scale application. In Lithuania QT-PCR is as a standalone<br />

test for a sub-set <strong>of</strong> prenatal samples, with the aim <strong>of</strong> minimising<br />

the identification <strong>of</strong> chromosome abnormalities <strong>of</strong> unknown clinical significance<br />

and reducing double testing. All prenatal samples are tested<br />

for trisomies 13, 18, 21, X and Y chromosomes using QT-PCR. Katyotype<br />

analysis is carried out only for referrals with NT >3 mm before 14<br />

weeks or >6 mm thereafter, ultrasound abnormalities (excluding single<br />

s<strong>of</strong>t marker), from families with a previous chromosome abnormality<br />

(excluding single s<strong>of</strong>t markers). During four years 1187 AF and 24 CVS<br />

were received. AF 22 % were karyotyped. 4.8 % AF and 4.2 % CVS<br />

were abnormal. All aneuploidies involving chromosomes 13, 18, 21, X<br />

and Y were detected with sensitivity and specificity 100%.Large scale<br />

application <strong>of</strong> QT-PCR has reduced the load <strong>of</strong> prenatal cytogenetics if<br />

all pregnancies are monitored by non invasive methods.<br />

P05.54<br />

Molecular karyotyping <strong>of</strong> whole genome amplified samples<br />

H. Raussi1 , M. Mäkinen2 , S. Ruosaari1 , A. Godenhjelm1 , P. Ollikka1 ;<br />

1 2 PerkinElmer <strong>Human</strong> Health, Turku, Finland, University Of Turku, Turku, Finland.<br />

Background: Array comparative genomic hybridization (array CGH)<br />

has been widely used for detection <strong>of</strong> copy number changes in tumors<br />

and genetic disorders. In the prenatal setting, however, where starting<br />

DNA amounts may be too low for array CGH, the feasibility <strong>of</strong> the technology<br />

remains to be defined. Although whole genome amplification<br />

(WGA) has potential for expanding the use <strong>of</strong> array CGH in analyses<br />

<strong>of</strong> few nanograms <strong>of</strong> DNA or even single cells, further information is<br />

needed about the putative bias WGA introduces to the genomic pr<strong>of</strong>iles.<br />

Methods: We performed WGA on DNA samples and analyzed the<br />

resulting genomic pr<strong>of</strong>iles by means <strong>of</strong> array CGH. The amplification<br />

was performed with GenomePlex ® (SigmaAldrich) products using few<br />

nanograms <strong>of</strong> DNA or few cells as a starting material. To assess possible<br />

bias introduced by WGA, the amplified test samples were hybridized<br />

using both the respective native and an amplified reference<br />

DNA as the reference. PerkinElmer’s Constitutional Chip ® platform and<br />

SpectralWare ® analysis s<strong>of</strong>tware were used in the array CGH analysis.<br />

Results and conclusions: Our results indicate that the Constitutional<br />

Chip ® platform works effectively for generating array CGH data from<br />

amplified test and reference samples. However, when native DNA is<br />

compared against the respective amplified DNA, specific chromosome<br />

regions continuously fail to amplify, especially as the amount <strong>of</strong> the<br />

starting material is decreased. The results show that detection <strong>of</strong> aneuploidies<br />

is not hampered by the sequence drop-out, yet micro-level<br />

changes may be missed owing to the biased amplification.<br />

P05.55<br />

Detection <strong>of</strong> fetal trisomies with a 19-plex QF-PcR using the<br />

novel Amplitaq Gold PcR 360 master mix<br />

R. Achmann1 , F. Stellmer1 , K. Held1 , H. Schulte1 , A. Sartori2 ;<br />

1 2 MVZ genteQ, Hamburg, Germany, Applied Biosystems GmbH, Darmstadt,<br />

Germany.<br />

In recent years quantitative fluorescent polymerase chain reaction<br />

(QF-PCR) with short tandem repeat markers (STR) have become the<br />

method <strong>of</strong> choice for the prenatal detection <strong>of</strong> the most common chromosome<br />

aneuploidies. The main advantages <strong>of</strong> QF-PCR are its accuracy<br />

and speed. Typically test results can be obtained within a few<br />

hours after sample receipt.<br />

We established an elaborated multiplex QF-PCR covering the chromosomes<br />

13, 18, 21 and X with a total <strong>of</strong> 19 polymorphic markers. Primers<br />

for amplification <strong>of</strong> markers were labeled with four different fluorescent<br />

dyes. PCR products were analyzed in parallel on a multicapillary<br />

electrophoresis instrument. We compared results obtained with our<br />

standard protocol using a chemically blocked hot start Taq polymerase<br />

with Applied Biosystems novel AmpliTaq Gold PCR 360 Master Mix.<br />

We were able to reduce cycling time from 2:45 hours to 2 hours with<br />

AmpliTaq Gold PCR 360 Master Mix without compromising the PCR<br />

yield, specificity and sensitivity. We observed reliable amplification <strong>of</strong><br />

marker alleles allowing us to correctly deduce fetal chromosomal aneuploidies<br />

from amniotic fluid and ‘chorionic villus’ samples.<br />

P05.56<br />

Quantitative analysis <strong>of</strong> foetal DNA in maternal circulation in<br />

gestational diabetes mellitus (GDm) pregnancies<br />

M. Zamanpoor1 , T. Karuppiah1 , R. Rosli1 , M. Yazid1 , Z. Husain2 ;<br />

1Clinical <strong>Genetics</strong> Unit, Department <strong>of</strong> Obstetrics and Gynaecology, Faculty <strong>of</strong><br />

Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia,<br />

2Department <strong>of</strong> Interdisciplinary Medicine, BIDMC, Harvard Medical School,<br />

Boston, MA, United States.<br />

Gestational Diabetes Mellitus (GDM) is a condition in which women<br />

without prior diagnosis <strong>of</strong> diabetes, show high levels <strong>of</strong> blood glucose<br />

during pregnancy. GDM affects 3-10% <strong>of</strong> pregnancies. Studies have<br />

shown that women with GDM have a higher risk <strong>of</strong> preeclampsia and<br />

that their <strong>of</strong>fsprings are at a higher risk for congenital malformations.<br />

Increased amount <strong>of</strong> cell free foetal DNA (cffDNA) in maternal plasma<br />

has been found in adverse pregnancies such as preeclampsia,<br />

gestational hypertension, foetal chromosomal aneuploidies, placental<br />

abnormalities, preterm labour and hyperemesis gravidarum. It was<br />

suggested that elevation <strong>of</strong> cffDNA in maternal plasma could be used<br />

for early identification <strong>of</strong> adverse pregnancies. The aim <strong>of</strong> our study<br />

was to determine the elevation <strong>of</strong> cffDNA levels in GDM pregnancies<br />

compared to normal pregnancies. In this study, twenty-three secondtrimester<br />

plasma samples from GDM pregnancies were compared with<br />

fourteen control samples <strong>of</strong> normal pregnancies, all carrying a singleton<br />

male foetus. The cffDNA concentrations were measured by quantitative<br />

real-time PCR amplification <strong>of</strong> SRY gene which is located on<br />

Y chromosome, using TaqMan dual labelled probe system. The mean<br />

<strong>of</strong> cffDNA levels for cases and controls were 3.47 and 5.64 genome<br />

equivalents/ml, respectively. No significant differences (P = 0.17) in<br />

the mean <strong>of</strong> cffDNA concentration were observed between GDM and<br />

normal pregnancies. In conclusion, GDM does not affect levels <strong>of</strong> maternal<br />

plasma cffDNA. Hence, if cffDNA is used as an additional serum<br />

marker in prenatal screening test in the future, our data suggests that<br />

cffDNA quantity will not require adjustment for GDM pregnancies.<br />

P05.57<br />

Evaluation <strong>of</strong> automated DNA extraction for non invasive<br />

prenatal diagnosis using free fetal DNA in maternal plasma<br />

E. Ordoñez1 , L. Rueda1 , P. Cañadas1 , C. Mediano2 , C. Fuster3 , V. Cirigliano1 ;<br />

1 2 General Lab, Barcelona, Spain, Hospital Vall d’Hebrón, Barcelona, Spain,<br />

3Universitat Autònoma de Barcelona, Barcelona, Spain.<br />

The use <strong>of</strong> free fetal DNA for non invasive prenatal detection <strong>of</strong> fetal<br />

sex and RhD status is part <strong>of</strong> the daily routine in several genetic centers.<br />

Automation <strong>of</strong> DNA extraction process simplifies sample handling<br />

allowing high throughput <strong>of</strong> samples. We evaluated the suitability <strong>of</strong><br />

using an automated DNA extraction procedure for ffDNA extraction in<br />

comparison with the most commonly used manual method.<br />

Fifty Blood samples collected in the first trimester <strong>of</strong> pregnancy from<br />

pregnant women with male fetuses were selected for this study. DNA<br />

extractions were performed by using 500µL <strong>of</strong> plasma for the QIAamp<br />

DSP Virus Kit (QIAgen Inc.) or 1mL <strong>of</strong> plasma for the COBAS AmpliPrep®<br />

DNA/RNA extractor from ROCHE. ffDNA was quantified by<br />

rtPCR amplification <strong>of</strong> the SRY gene and yield (GE/mL) was calculated<br />

for both extraction methods.<br />

SRY amplification was detectable in all samples independently from<br />

the extraction procedure and no false negative results were observed.<br />

ffDNA quantity obtained by the manual extraction method was higher<br />

than using the automated extraction with a mean <strong>of</strong> 259,43GE/mL and<br />

109,47GE/mL plasma respectively.<br />

The lower ffDNA yield obtained using an automated DNA extraction<br />

procedure does not affect the efficiency <strong>of</strong> detecting fetal specific sequences<br />

in maternal plasma by rtPCR. Automated DNA extraction allows<br />

high throughput <strong>of</strong> samples (up to 72 samples/run) in a closed<br />

system thus greatly reducing the risk <strong>of</strong> cross contamination; it also<br />

requires less sample manipulation reducing overall costs and hands<br />

on time.

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