The basic NIPT test examines chromosome 21 trisomy, chromosome 18 trisomy, chromosome 13 trisomy, and sex chromosomes, while the All Chromosome Aneuploidy Test examines all chromosomes from 1 to 22 and all sex chromosomes for aneuploidy.
From the table below, we can say that the chorionic villus sampling is positive at a rate of 0.56%, or about 1 in 200, and the amniotic fluid test is positive at a rate of 0.05%, or about 1 in 2000.
Positive rates of all chromosome aneuploidy
in chorionic villus biopsy and amniotic fluid testing
| Trisomy 21, 18, 13 | Other trisomies | |
|---|---|---|
| # of samples in chorionic villus sampling | 5.06% (532 out of 10,511) | 0.56% (59 out of 10,511) |
| # of samples in amniotic fluid testing | 1.02% (748 out of 73,268) | 0.05% (30 out of 73,268) |
| # of samples from both chorionic villus sampling and amniotic fluid testing | 2.1% (235 out of 11,066) | 0.12% (13 out of 11,066) |
1. Konialis C, Pangalos C. Dilemmas in prenatal chromosomal diagnosis revealed through a single center’s 30 years’ experience and 90,000 cases. Fetal Diagn Ther 2015; 38(3):218-232.
2. Comas C, Echevarria M, Rodríguez I, Serra B, Cirigliano V. Prenatal invasive testing: a 13-year single institution experience. J Matern Fetal Neonatal Med 2014 Aug;27(12):1209-12.
Reports by trisomy type that were positive for All Chromosome Aneuploidy Tests
(excluding mosaic)
| Trisomy 1 | Blighted Ovum |
|---|---|
| Trisomy 2 | No survival |
| Trisomy 3 | No reports of positives |
| Trisomy 4 | Rare: No survival |
| Trisomy 5 | No survival |
| Trisomy 6 | No survival |
| Trisomy 7 | No survival |
| Trisomy 8 | No survival |
| Trisomy 9 | There is a survival case. |
| Trisomy 10 | No survival |
| Trisomy 11 | No survival |
| Trisomy 12 | No survival |
|---|---|
| Trisomy 13 | There is a survival case. |
| Trisomy 14 | No survival |
| Trisomy 15 | There is a survival case. |
| Trisomy 16 | No survival |
| Trisomy 17 | No survival |
| Trisomy 18 | There is a survival case. |
| Trisomy 19 | Extremely rare: No survival |
| Trisomy 20 | There is a survival case. |
| Trisomy 21 | There is a survival case. |
| Trisomy 22 | There is a survival case. |
Frequently Asked Questions about All Chromosome Testing
Q: Will a full chromosome test show all chromosomal abnormalities in the fetus?
A: The all-chromosome test examines autosomes (chromosomes 1-22) and ” abnormal numbers” such as trisomy, which has three sex chromosomes, and monosomy, which has only one sex chromosome.
Testing for structural abnormalities such as chromosome deletions and duplications as well as abnormalities in the number of chromosomes requires testing for all autosomal whole region partial deletion/duplication disease*.
Please see ‘Test Plans‘ for details on the applicable test plan.
For more information on all autosomal whole region partial deletion/duplication diseases, please refer to ‘What is a whole autosomal partial deletion/duplication disease?‘ page.
*Limited, however, to anomalies of 7 million bases or more.
