Down Syndrome Screening in India: Are We There Yet?
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ABSTRACT:
SUBMITTER: Manikandan K
PROVIDER: S-EPMC5676577 | biostudies-other | 2017 Dec
REPOSITORIES: biostudies-other
Publications
Down Syndrome Screening in India: Are We There Yet?
Manikandan K K Seshadri Suresh S
Journal of obstetrics and gynaecology of India 20170817 6
Down syndrome is the most common cause of intellectual disability among live born children and is amenable to prenatal detection. Screening for Down syndrome on a population basis requires a thorough understanding of the principles involved in the screening tests. We discuss the rationale behind the commonly available screening tests and the Indian scenario in this setting. ...[more]
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Project description:OBJECTIVE:To estimate the effectiveness of second-trimester genetic sonography in modifying Down syndrome screening test results. METHODS:The First and Second Trimester Evaluation of Risk (FASTER) aneuploidy screening trial participants were studied from 13 centers where a 15- to 23-week genetic sonogram was performed in the same center. Midtrimester Down syndrome risks were estimated for five screening test policies: first-trimester combined, second-trimester quadruple, and testing sequentially by integrated, stepwise, or contingent protocols. The maternal age-specific risk and the screening test risk were modified using likelihood ratios derived from the ultrasound findings. Separate likelihood ratios were obtained for the presence or absence of at least one major fetal structural malformation and for each "soft" sonographic marker statistically significant at the P<.005 level. Detection and false-positive rate were calculated for the genetic sonogram alone and for each test before and after risk modification. RESULTS:A total of 7,842 pregnancies were studied, including 59 with Down syndrome. Major malformations and 8 of the 18 soft markers evaluated were highly significant. The detection rate for a 5% false-positive rate for the genetic sonogram alone was 69%; the detection rate increased from 81% to 90% with the combined test, from 81% to 90% with the quadruple test, from 93% to 98% with the integrated test, from 97% to 98% with the stepwise test, and from 95% to 97% with the contingent test. The stepwise and contingent use of the genetic sonogram after first-trimester screening both yielded a 90% detection rate. CONCLUSION:Genetic sonography can increase detection rates substantially for combined and quadruple tests and more modestly for sequential protocols. Substituting sonography for quadruple markers in sequential screening was not useful. LEVEL OF EVIDENCE:II.
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Project description:BackgroundThe incidence of Down syndrome (DS) in Egypt varies between 1:555 and 1:770 and its screening by triple test is becoming increasingly popular nowadays. Results, however, seem inaccurate due to the lack of Egyptian-specific information needed for risk calculation and a clear policy for programme implementation. Our study aimed at calculation and validation of the triple marker medians used in screening Egyptian females as well as to recommend programme conventions to unify screening in this country.MethodsThe study was conducted on 668 Egyptian women, in weeks 15-20 of pregnancy as proven by sonar. Chorionic gonadotropin (CG), α-fetoprotein (AFP) and unconjugated oestriol (uE3) were measured on Siemens Immulite analyzer. Medians of the three parameters were calculated, regressed against gestational age (GA) and weighted by the number of participants/week. Equations were derived to adjust each parameter to the maternal weight and were centered on the median Egyptian weight. Prisca software was fed with the above data, multiples-of-median (MoM) and DS risks were calculated and the screening performance was evaluated at a mid-trimester risk cutoff of 1:270.ResultsLog-linear [AFP/uE3 = 10(A+B*GA)] and exponential equations [CG = A*e (B*GA)] were derived and the regressed medians were found to follow similar patterns to other Asian and Western medians. Oestriol was always lowest (even halved) while CG and AFP were intermediate. A linear reciprocal model best fitted weight distribution among Egyptians and successfully adjusted each parameter to a weight of 78.2 kg. Epidemiological monitoring of these recommendations revealed satisfactory performance in terms of 6.7% initial positive rate and 1.00 grand MoM.ConclusionsAdoption of the above recommendations is hoped to pave the way to a successful DS screening programme tailored to Egyptian peculiarities.
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Project description:The Ts1Cje mouse strain (Sago, 1998) contains a segmental trisomy of mouse chromosome 16 orthologous to the region of human chromosome 21 commonly associated with Down Syndrome. In this study, fetuses were obtained from wildtype mothers bred with either wildtype or Ts1Cje males. Gene expression profiles in fetal liver and placenta of wildtype and Ts1Cje fetuses were compared, to identify potential markers for application in human prenatal DS screening. A 48 array study with 24 arrays for placenta and 24 for fetal liver. For each tissue we used RNA from 24 individual embryos, i.e. six male and six female embryos from both genotypes.
2011-05-11 | E-GEOD-24272 | biostudies-arrayexpress
Project description:The Ts1Cje mouse strain (Sago, 1998) contains a segmental trisomy of mouse chromosome 16 orthologous to the region of human chromosome 21 commonly associated with Down Syndrome. In this study, fetuses were obtained from wildtype mothers bred with either wildtype or Ts1Cje males. Gene expression profiles in fetal liver and placenta of wildtype and Ts1Cje fetuses were compared, to identify potential markers for application in human prenatal DS screening.
2011-05-11 | GSE24272 | GEO
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