Detection Rate Of Chromosomal Abnormalities Research Articles

The role of ductus venosus blood flow assessment in screening for chromosomal abnormalities at 10-16 weeks of gestation.

To evaluate the role of ductus venosus blood flow assessment at 10-16 weeks' gestation in screening for chromosomal abnormalities. Ductus venosus blood flow was prospectively evaluated in 1371 consecutive pregnancies between 10 and 16 weeks of gestation. The pulsatility index for veins was calculated. All cases were screened for chromosomal defects combining maternal age and fetal nuchal translucency thickness. A chromosomal abnormality was found in 20 cases. The overall detection rate, specificity, positive predictive value, negative predictive value and odds ratio for chromosomal abnormalities were 65%, 95.7%, 18.3%, 99.5% and 41 (95% CI 16-108), respectively, when using the 95th centile pulsatility index as a cut-off. These preliminary results suggest that evaluation of the ductus venosus pulsatility index at 10-16 weeks' gestation is a useful second-line screening test for chromosomal defects. A combination of nuchal translucency measurement and ductus venosus assessment might increase specificity while maintaining an optimal detection rate for chromosomal abnormalities. Such a policy could identify 55% of all chromosomal abnormalities and about 69% of autosomal trisomies, reducing the need for invasive testing to less than 1%.

Contribution of Comparative Genomic Hybridization and Fluorescence in situ Hybridization to the Detection of Chromosomal Abnormalities in B-Cell Chronic Lymphocytic Leukemia

Background: B-chronic lymphocytic leukemia (B-CLL), the most common type of leukemia in Western Europe and the United States, is characterized by clonal chromosomal abnormalities detected in almost half of the studied patients. The precise determination of chromosomal changes helps to indicate the prognosis and to understand the pathogenesis of CLL. Methods and Patients: We applied conventional cytogenetics (CC), FISH and comparative genomic hybridization (CGH) to the investigation of clonal abnormalities in 88 B-CLL patients at the time of diagnosis. Results: By using CC of bone marrow cells without any stimulation, non-random chromosomal changes were found in 17 (19%) of 88 patients.The employment of FISH and CGH revealed chromosomal changes in additional 33 patients, thus increasing the detection rate of chromosomal abnormalities to 57%. The most common abnormalities detected in our patients included deletions of 13q in 16 cases (18%), followed by trisomy of chromosome 12 in 12 patients (13%), deletions of 11q in 10 patients (11%) and deletions of 17p in 10 patients (11%). A statistically significant correlation between higher disease activity and the presence of deletions 11q and 17p was observed. Conclusion: The addition of FISH and CGH to CC in 88 B-CLL patients improved the detection of clonal chromosomal changes from 19 to 57%. The most frequent chromosomal change was deletion of 13q14 (18%). Deletions of 11q23 and 17p13 were found in patients with higher clinical disease activity. Our results underline the importance of employing FISH and CGH techniques in CLL patients. CC without any stimulation has a low detection rate and is not suggested for detection of chromosomal changes in CLL.

WS06‐03Ultrasound‐detected heart defects associated with aneuploidy

In North America second trimester genetic ultrasound is offered to patients at risk for trisomy 21 and other chromosomal abnormalities who decline invasive testing. In most major studies in which the prevalence of ultrasound markers used for genetic ultrasound are reported, congenital heart defects are identified in less than 10% of fetuses. When one considers that over 50% of fetuses with trisomy 21 and 90% of fetuses with trisomies 13 and 18 have structural malformations of the heart, the question should be raised as to why the wide discrepancy in prevalence and detection rate of heart defects in these fetuses. The purpose of this presentation is to review the prevalence of CHD in fetuses with trisomy 21, trisomies 13 and 18, and all fetuses with chromosomal defects that were identified following second trimester amniocentesis. To ascertain the presence or absence of CHD, each fetus underwent a fetal echocardiographic study using real‐time and color Doppler ultrasound at the time of genetic amniocentesis.The results of the study demonstrated the following: The detection rate for trisomy 21 (n = 80) increased from 62% to 91% when examination of the fetal heart was performed. The detection rate for trisomy 18 (n = 30) increased from 84%% to 97% when the cardiovascular system was evaluated. For fetuses with any chromosomal abnormality (n = 103) advanced maternal age were examined, the examination of the heart increased the detection rate from 61% to 85%.Given the above findings, the inclusion of the fetal echocardiographic evaluation of the fetus significantly increased the detection rate for the above three groups of fetuses. If physicians and/or sonographers desire to increase the ultrasound detection rate for chromosomal abnormalities, examination of the fetal cardiovascular system must occur.

The advantages of using triple-marker screening for chromosomal abnormalities

OBJECTIVE: Our purpose was to assess the utility of triple-marker serum screening for chromosomal abnormalities. STUDY DESIGN: Our laboratory received 10,605 samples that were between 15 and 22 weeks' gestation for maternal serum screening of chromosomal abnormalities. Triple-maker maternal serum screening consisted of α-fetoprotein, human chorionic gonadotropin, and unconjugated estriol in conjunction with maternal age. Women ≥35 years old were first offered amniocentesis. If they refused amniocentesis, they were offered the screening test. A second-trimester risk for trisomy 21 ≥ 1:270 was considered screen positive. Patients were screen positive for trisomy f8 if all three markers were low: α-fetoprotein ≤0.75 multiples of the median, unconjugated estriol ≤ 0.60 multiples of the median, and human chorionic gonadotropin ≤0.55 multiples of the median. RESULTS: The initial screen-positive rate was 8.3% (880 women); amniocentesis was offered to 766 (7.2%). Twelve of 16 ascertained cases of trisomy 21 (75%), two of three cases of trisomy 18 (67%), five cases of 45,X karyotype, and one case each of 45,X/46,XX, 47,XXY, 47,XYY, 46,XX,ins(2)(q21p13p15)mat, and 69,XXX karyotypes were identified in the screen-positive patients. All four known cases of trisomy 21 in the 886 women ≥35 years old who were screened were detected, with a 21% false-positive rate. Omitting unconjugated estriol from our screening program would have resulted in detecting nine of 16 trisomy 21 and six of 12 other chromosomal abnormalities. The false-positive rate would have remained the same. CONCLUSION: In our sample cohort addition of unconjugated estriol to the screening program resulted in an increased detection rate of chromosomal abnormalities with no change in the false-positive rate. Considering the advancement in screening for chromosomal abnormalities, maternal age alone as an indicatio for amniocentesis should be reevaluated.