Rare autosomal aneuploidy Fact sheet for genetic counseling
Rare autosomal aneuploidy (RAA) These are trisomies and monosomies of chromosomes 1 – 12, 14 – 17, 19, 20 What is the test accuracy? and 22 as well as monosomies of chromosomes 13, 18 and 21. Sensitivity and specificity for rare autosomal aneuploidy (RAA); including known mosaics4
Estimated incidence per chromosomal aberration* Sensitivity Specificity
Estimate % (n/N) Trisomy 21 Trisomy 18 Trisomy 13 SCA RAA 96.4% 99.80% (27/28) (2,001/2,005)
1 1 1 2 3 0.30% 0.10% 0.10% 0.48% 0.34% 2-sided 95% CI
Incidence 82.3%, 99.49%, 99.4% 99.92% 0.50% 0.48% + 0.34%
* for SCA and RAA the incidences of the different chromosomal aberrations are summarized
What does a positive test result mean? Please note: NIPT is a screening test; false Your patient’s NIPT result suggests the presence of a rare autosomal aneuploidy. positive results can occur. The You should discuss the result and the potential clinical implications with your patient. actual chance for the pregnancy According to recommendations from international professional associations, further to have a rare autosomal medical clarification, usually in the form of invasive diagnostics, is urgently aneuploidy depends on many recommended to validate the test result. We kindly request a response in the event of factors, including the patient’s inconsistent results. clinical and family history.
Chromosomal anomaly Confined placental in the fetus mosaicism Clinical presentation after a positive test result is variable, and is chromosome dependent. Some cases will have no apparent clinical findings. Potential clinical outcome in the case of a positive test result Literature references Placental insufficiency Mardy A, Wapner RJ. Confined placental mosaicism and its Pre-eclampsia impact on confirmation of NIPT results. Am J Med Genet C Semin Premature birth Med Genet. 2016;172(2):118-22. Kalousek DK, Barrett I. Confined Miscarriage placental mosaicism and stillbirth. Pediatr Pathol Januar-Februar IUGR 1994;14(1):151-9. IUFD Kalousek DK. Confined placental mosaicism and intrauterine Fetal anomalies development. Pediatr Pathol. 1990;10(1-2):69-77. No clinical findings
www.lifecodexx.com WM-1292-EN-001 A positive NIPT result for certain autosomal trisomies is associated with an in- creased risk of confined placental mosaicism (CPM) associated with an increased risk of uniparental disomy (UPD).
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1 Galjaard RJ et al. Implementing NIPT as part of a national prenatal screening program: The Dutch TRIDENT studies. Prenat Diagn 2018;38(S1):8 2 Scott et al. Rare autosomal trisomies: Important and not so rare. Prenat Diagn 2018;38:765-71 3 Pertile MD Genome-wide cell-free DNA-based prenatal testing for rare autosomal trisomies and subchromosomal abnormalities. In: Nonivasive Prenatal Testing, Academic Press 2018, Eds Page-Christiaens and Klein 4 Illumina VeriSeq NIPT Solution v2 Packungsbeilage, Dokument-Nr. 1000000086774 v02 DEU, August 2019 5 Wegner und Stumm, medgen 2011; 23:457-462 www.lifecodexx.com