Objective
To evaluate if non‐invasive prenatal testing (NIPT) affects livebirth (LB) prevalence of Down syndrome (DS) in the Netherlands.
Method
Data from clinical genetics laboratories and the ...Working Party on Prenatal Diagnosis and Therapy (2014–2018) and previous published data (1991–2013) were used to assess trends for DS LB prevalence and reduction percentage (the net decrease in DS LBs resulting from selective termination of pregnancies). Statistics Netherlands provided general population data.
Results
DS LB prevalence increased from 11.6/10,000 in 1991 to 15.9/10,000 in 2002 (regression coefficient 0.246 95% CI: 0.105–0.388; p = 0.003). After 2002, LB prevalence decreased to 11.3/10,000 in 2014 and further to 9.9/10,000 in 2018 (regression coefficient 0.234 (95% CI: −0.338 to −0.131; p < 0.001). The reduction percentage increased from 26% in 1991 to 55.2% in 2018 (regression coefficient 0.012 (95% CI: 0.010–0.013; p < 0.001)). There were no trend changes after introducing NIPT as second‐tier (2014) and first‐tier test (2017).
Conclusions
Introducing NIPT did not change the decreasing trend in DS LB prevalence and increasing trend in reduction percentage. These trends may be caused by a broader development of more prenatal testing that had already started before introducing NIPT.
Key points
What's already known about this topic?
The introduction of NIPT changed the landscape in prenatal screening worldwide.
No long‐term population‐based study on the impact of NIPT on DS LB prevalence has been published.
What does this study add?
This study shows how to calculate DS LB prevalence in the absence of a national registration program.
Introducing NIPT caused no trend changes in DS LB prevalence and reduction percentage in the Netherlands.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Using genome-wide noninvasive prenatal screening (NIPS), we detected a 20-megabase specific deletion starting at 10q25 in eight pregnancies. The deletion could not be confirmed by invasive testing. ...Since all 10(q25→qter) deletions started close to the FRA10B fragile site in 10q25, we investigated whether the pregnant women were indeed carriers of FRA10B.
We performed NIPS analysis for all autosomes using single-read sequencing. Analysis was done with the WISECONDOR algorithm. Culture of blood lymphocytes with bromodeoxyuridine was used to detect FRA10B expansions. Fluorescence in situ hybridization and array analysis were used to find maternal and/or fetal deletions.
We confirmed the presence of a FRA10B expansion in all four tested mothers. Fluorescence in situ hybridization and array analysis confirmed the presence of a maternal mosaic deletion of 10(q25→qter).
The recurring 10(q25→qter) deletion detected with NIPS is a false-positive result caused by a maternal low-level mosaic deletion associated with FRA10B expansions. This has important consequences for clinical follow-up, as invasive procedures are unnecessary. Expanded maternal FRA10B repeats should be added to the growing group of variants in the maternal genome that may cause false-positive NIPS results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PurposeNoninvasive prenatal screening (NIPS) using cell-free DNA in maternal blood is highly sensitive for detecting fetal trisomies 21, 18, and 13. Using a genome-wide approach, other chromosome ...anomalies can also be detected. We report on the origin, frequency, and clinical significance of these other chromosome aberrations found in pregnancies at risk for trisomy 21, 18, or 13.MethodsWhole-genome shallow massively parallel sequencing was used and all autosomes were analyzed.ResultsIn 78 of 2,527 cases (3.1%) NIPS was indicative of trisomy 21, 18, or 13, and in 41 (1.6%) of other chromosome aberrations. The latter were of fetal (n = 10), placental (n = 22), maternal (n = 1) or unknown (n = 7). One case lacked cytogenetic follow-up. Nine of the 10 fetal cases were associated with an abnormal phenotype. Thirteen of the 22 (59%) placental aberrations were associated with fetal congenital anomalies and/or poor fetal growth (<p10), which was severe (<p2.3) in six cases.ConclusionGenome-wide NIPS in pregnancies at risk for trisomy 21, 18, or 13, reveals a chromosomal aberration other than trisomy 21, 18 or 13 in about one-third of the abnormal cases. The majority involves a fetal or placental chromosome aberration with clinical relevance for pregnancy management.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
SRRM2 encodes the SRm300 protein, a splicing factor of the SR-related protein family characterized by its serine- and arginine-enriched domains. It promotes interactions between messenger RNA and the ...spliceosome catalytic machinery. This gene, predicted to be highly intolerant to loss of function (LoF) and very conserved through evolution, has not been previously reported in constitutive human disease.
Among the 1000 probands studied with developmental delay and intellectual disability in our database, we found 2 patients with de novo LoF variants in SRRM2. Additional families were identified through GeneMatcher.
Here, we report on 22 patients with LoF variants in SRRM2 and provide a description of the phenotype. Molecular analysis identified 12 frameshift variants, 8 nonsense variants, and 2 microdeletions of 66 kb and 270 kb. The patients presented with a mild developmental delay, predominant speech delay, autistic or attention-deficit/hyperactivity disorder features, overfriendliness, generalized hypotonia, overweight, and dysmorphic facial features. Intellectual disability was variable and mild when present.
We established SRRM2 as a gene responsible for a rare neurodevelopmental disease.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
False-negative cell-free DNA (cfDNA) screening results involving Down syndrome are rare, but have high clinical impact on patients and their healthcare providers. Understanding the biology behind ...these results may allow for improved diagnostic follow-up and counseling. In 5 different centers offering cfDNA prenatal screening, 9 false-negative results were documented in 646 confirmed cases of trisomy 21; a false-negative rate of 1.4% (95% CI, 0.7-2.6). False-negative results included 4 cases of classical trisomy 21 and 5 cases with a de novo 21q;21q rearrangement. Two out of five rearrangements had molecular studies and were confirmed as isochromosomes. When combined with reports from the cfDNA screening literature, 8 out of 29 (28%) Down syndrome cases with a false-negative "non-invasive prenatal test" (NIPT) were associated with a 21q;21q rearrangement, compared with 2% reported in live born children with Down syndrome. In our laboratory series, evidence for placental or fetal mosaicism was present in 3 out of 3 true-positive cases involving a 21q;21q rearrangement and was confirmed in one false-negative case where placental material was available for study. Isochromosome 21q rearrangements are thus overrepresented among false-negative cfDNA screening results involving Down syndrome. Postzygotic isochromosome formation leading to placental mosaicism provides a biological cause for the increased prevalence of these rearrangements among false-negative cases. For clinical practice, a low trisomic fraction (z-score or equivalent measure) relative to the fetal fraction suggests placental mosaicism. Care should be taken as these cases may not reflect confined placental mosaicism, but rather full trisomy in the presence of a placenta containing normal cells.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Trisomy 4 mosaicism: Delineation of the phenotype Bouman, Arjan; van der Kevie-Kersemaekers, Anne-Marie; Huijsdens-van Amsterdam, Karin ...
American journal of medical genetics. Part A,
April 2016, Volume:
170A, Issue:
4
Journal Article
Double aneuploidy mosaicism of two different aneuploidy cell lines is rare. We describe for the first time a double trisomy mosaicism, involving chromosomes 7 and 13 in a fetus presenting with ...multiple congenital anomalies. No evidence for chimerism was found by DNA genotyping. The origin of both trisomies are consistent with isodisomy of maternal origin. Therefore, it is most likely that the double trisomy mosaicism arose from two independent events very early in embryonic development. The trisomy 7 and 13 cells were shown to be of maternal origin.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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