Compilation of NIPT test results for more than
10,000 pregnant women in Japan

NIPT testing for pregnant women in Japan
using Illumina equipment (10,007 cases)

Hiro Clinic NIPT has performed more than 10,000 tests (June 2020 – June 2021). In collaboration with Second Tokyo Clinical Laboratory, we have examined 10,007 pregnant women who took the Full set plan available in Hiro Clinic NIPT, and we determined what are the most appropriate tests for pregnant women in Japan and which tests are appropriate for which age groups.

This data analysis was performed under the following conditions:

  • No age limit for testing
  • No restriction on
    target chromosomes
  • Limited to pregnant
    women in Japan

What results can be expected without the ’35+ age limit’ recommended by the NIPT Consortium? This has not been verified to date.
Data on all other autosomes (including sex chromosomes) and whole region partial deletions and duplications have not been reported in Japan, although the positivity rates of chromosomes 21, 18, and 13 have been reported.

In NIPT studies around the world, it is known that genetic disorders have ethnic and regional characteristics.
However, despite the availability of various research data, mainly from Europe and the U.S. but also from Asia, there have been no reports of genetic disease data exclusively on pregnant women in Japan.

Hiro Clinic NIPT hopes that the ‘NIPT test results of more than 10,000 pregnant women in Japan’ derived from our past tests will be made public and will help pregnant women to choose the right test. Hiro Clinic NIPT places the utmost importance on protecting the right to know of all concerned parties, including pregnant women. (As of June 21, 2021)

Total # of people10,007
Over 35 years old5,00250.0%
Under 35 years old5,00550.0%
Oldest positive individual47 years old
Youngest positive individual24 years old
Number of positive patients2452.45%
Positive cases over 35 years old1753.50%
Positive cases under 35 years old701.40%

According to the latest examination statistics, only 50% of pregnant women are over the age of 35.
This is a clear indication that more and more pregnant women under the age of 35 come to be examined.
At Hiro Clinic NIPT, the overall positivity rate is 2.45%; the positivity rate for those over 35 years old is 3.50%, which is 2.5 times higher than the 1.40% positivity rate for those under 35 years old. This is because there are actually about 3 times more births under the age of 35, so the estimated number of abnormalities under the age of 35 is about 1.2 times (= 1.40 / 3.50 X 3) higher than the number of abnormalities over the age of 35.

Source: Hiro Clinic Research

Source: Hiro Clinic Research

Age of Pregnant WomenTrisomy 21
Trisomy 18
Trisomy 13
Sex chromosomeOther autosomesAll autosomal whole region partial deletions/duplicationsTotal
Total Positive in every case674416315244254
Number of all positive individuals674416315235245
Over 35
years old
Under 35
years old

※ Cases with multiple diseases are counted individually.

Source: Hiro Clinic Research

Of those who tested positive, 27.35% had Chromosome 21 trisomy, 17.96% had Chromosome 18 trisomy, and 6.53% had Chromosome 13 trisomy, accounting for half of the total. On the other hand, aneuploidy (abnormal number of chromosomes) of chromosomes other than 13, 18, and 21 accounted for 35% of the total, including 21% of autosomes and 13% of sex chromosomes.

Source: Hiro Clinic Research

Source: Hiro Clinic Research

Whole region partial deletions and duplications may have various clinical findings depending on their size and location. However, since the number of whole region partial deletions and duplications detected by Hiro Clinic NIPT is more than 7 million bases, even if 2% of them are considered to be in the exonic region, monosomy and trisomy of approximately 140,000 bases are likely to cause some disorders in patients with the disease.

Testing coverage of 10,007 NIPT tests (June 2021)

Test coverage is the percentage of cases that are positive for the selected test plan.

 Chro.21Chro.18Chro.13Sex chromosomeOther autosomesAll Autosomal Regions Partial deletion/duplication
Positive Location674416315244
Number of Positive Individuals674416315235

The bar graph above shows the numerical ‘Test Coverage Percentage’ of the test plans that are frequently chosen by pregnant women at Hiro Clinic NIPT.
The test coverage rate is of the minimum plan is 51%, while the Over35 plan, which is recommended for pregnant women over 35 years old, has a test coverage rate of 85%. The 51% test coverage means that 49% of the diseases are returned negative.
The second plan from the left is the ‘Recommended Plan’ of Hiro Clinic NIPT, which is a cost-effective plan with only selected test items that have been tested positive by 10,007 people. For those who would like to ensure complete coverage of results, we recommend the Full Set Plan.