It is up to the patient to decide whether it is necessary or not and we, the healthcare providers, can only provide information. 12 years have already passed since the test for trisomy 21 only became available in 2011. In the meantime, technology has advanced. Our mission is to provide state-of-the-art NIPT.
Certified centres recommend testing only for 21, 18 and 13 trisomy. We often hear that other tests are unnecessary. Hiro Clinic nevertheless offers a range of other tests. This is because the results of these tests are not only less frequent in the aggregate, but also have an impact on the mother’s body. We do not have actual data on the frequency and impact of these tests because we do not carry them out at the certified facilities. (It may be that they just don’t publish them.) Data on aneuploidy and partial deletions and partial duplications other than numbers 21, 18 and 13 exist at Hiro Clinic because we keep statistics, so we would like to compare these with those from other countries. The following are the extracted test results from the Hiro Clinic.
| Number of samples 29270 | People | Percentage |
| Chromosome 13 trisomy | 43 | 0.15% |
| Aneuploidy of all chromosomes (except 13, 18 and 21) | 179 | 0.59% |
| Partial deletion-partial duplication | 150 | 0.51% |
I would like to try to obtain information from abroad from the above-mentioned website. This is a website that only experts can see, so I will try to translate it briefly. (Anyone can look at it, but it is difficult because of all the jargon)
① First of all, the top page. I will put the translated version on the website. Where the expressions we use are different, we have supplemented them in red. After that, we will put a digest of the reports from each country. There are no major differences between the Hiro Clinic dates in any of them.
Mission of the Global NIPT Consortium
The Global NIPT Consortium is a group established by Illumina and other organisations with experience in cell-free DNA (cfDNA)-based prenatal screening (also known as non-invasive prenatal testing, NIPT) for chromosomal abnormalities. Its members have a significant interest in creating a global forum to generate evidence and awareness of the utility and best practice of NIPT for conditions beyond the common aneuploidy of 21, 18 and 13 trisomy (extended NIPT). ＜＝We name it here as Extended NIPT.
What is extended NIPT?
When NIPT first became available in 2011, it was limited to 21 trisomy, but eventually added the ability to screen for 18 and 13 trisomy and certain sex chromosome abnormalities (SCA). Since then, over 700 000 results on extended NIPT have been reported in 19 publications1. Extended NIPT has enabled the identification of all chromosomal sex chromosome abnormalities, including common trisomies (including chromosomes 21, 18 and 13), rare autosomal aneuploidies, SCA and CNVs of at least 7 Mb <= what we call a partial deletion partial duplication. , allowing a comprehensive view of these diseases. The population incidence of these disorders has been shown to be higher than 18 and 13 trisomy, with subsequent risk of adverse outcomes such as miscarriage, fetal growth restriction, stillbirth, single parent dysomy and associated risks, spontaneous preterm birth and foetal karyotype abnormalities. With associated phenotypes. 2,3,4 Furthermore, recent publications have shown that 25% of positive screening results may be missed if NIPT is limited to 21, 18 and 13 trisomy and sex chromosome abnormalities. 5 An expanded NIPT offers the opportunity to screen for these collectively common conditions that may affect the health and management of pregnancy.
- Data on file. Illumina, Inc. 2021
- Van Opstal et al (2018). Origin and Clinical relevance of chromosomal aberrations other than the common trisomies detected by genome-wide NIPT: results of the TRIDENT study. Genetics in Medicine, 20(5): 480-485.
- Pertile et al (2017). Rare autosomal trisomies, revealed by maternal plasma DNA sequencing, suggest increased risk of feto-placental disease. Science Translational Medicine, 9(405): 1-11.
- Scott et al (2018). Rare autosomal trisomies: Important and not so rare. Prenatal Diagnosis, 38(10): 765-771.
- Soster et al (2021). Three years of clinical experience with a genome-wide cfDNA screening test for aneuploidies and copy-number variants. Genetics in Medicine, 23(7): 1349-1355.
- Meij et al (2019). TRIDENT-2: National Implementation of Genome-Wide Non-Invasive Prenatal Testing as a First Tier Screening Test in the Netherlands. American Journal of Human Genetics, 105: 1-11.
②Next, let’s look at the reports from Belgium, which does the most.
Results of publicly funded national primary non-invasive pre-natal screening
Belgium was the first country to offer and fully reimburse NIPT as a primary screening option for all pregnant women. In this publication, a consortium of all Belgian genetic centres reports on their two-year clinical experience of offering extended NIPT as a primary testing option to all pregnant women. Of the 153,575 pregnancies screened, rare autosomal trisomies and partial deletions/duplications were found in 0.23% and 0.07% of cases, respectively. Invasive diagnostic obstetric procedures were reduced by 52%. The authors conclude that the extended NIPT approach has been successfully implemented in Belgian antenatal care and could serve as a framework for other countries offering NIPT.
③The Netherlands
Origin and clinical relevance of chromosome aberrations other than common trisomy detected by genome-wide NIPS: results of the TRIDENT study
This publication demonstrated the potential clinical utility of using extended NIPT to detect chromosomal abnormalities other than common aneuploidy. In this study population, 1.6% of cases undergoing extended NIPT were positive for screening for rare chromosomal abnormalities, which are rare autosomal trisomies or large partial deletions/duplications. Of these cases, 60% were associated with adverse pregnancy outcomes such as abnormal foetal phenotype or intrauterine growth restriction.
④United States
Genome-wide cell-free DNA screening: focus on copy number variation
This publication focuses on 490 (0.56%) cases from a cohort of 86,902 extended NIPT samples that screened positive for at least one partial chromosome deletion/duplication. Diagnostic results were obtained in 50% of these cases and PPVs were found to exceed 70%.
⑤China
Clinical utility of non-invasive prenatal screening for expanded chromosome disease syndromes
This publication examined the clinical outcomes of extended NIPT for both aneuploidy and genome-wide microdeletion/microduplication syndromes in an all-risk pregnancy population. A cohort of 94,085 patients with singleton pregnancies were prospectively enrolled. The extended NIPT detected clinically significant foetal chromosome abnormalities in 1.2% of samples and calculated the respective PPVs for screening positive abnormalities.
