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Technical characteristics of the IONA® test following Post-market surveillance on 9,575 singleton and monochorionic twin pregnancies

 The IONA® 

Nx test

 Sensitivity

(Detection or True Positive Rate)

 False Negative Rate (FNR)

 Specificity (True Negative Rate)

False Positive Rate (FPR) 

 Positive predictive value (PPV)

(Precision)*

Negative predictive value (NPV)* 

 

 The proportion of truly affected pregnancies that screen positive.

The proportion of pregnancies that have the syndrome but have screened negative.

The proportion of truly unaffected pregnancies that screen negative. 

 The proportion of pregnancies that do not have the syndrome, but have screened positive.

The likelihood that a screened positive pregnancy is truly affected with a trisomy.

The likelihood that a screened negative pregnancy really doesn't have a trisomy.

 Trisomy 21

(Down's sydnrome)

 >99.99%

(200/200)

<0.001%

(0/200)

99.97%

(9,374/9,375)

 0.01%

(1/9,375)

99.50%

(200/201)

 >99.99%

(9,374/(9,375-201)

 Trisomy 18 

(Edwards' syndrome)

98.33%

(59/60)

1.67%

(1/60)

99.97%

(9,513/9,515)

0.02%

(2/9,515)

96.72%

(59/61)

99.99%

(9,513/9,575-61))

Trisomy 13

(Patau's syndrome)

>99.99%

(15/15)

<0.001%

(0/15)

>99.99%

(7,560, 7569)

<0.001%

(0/9,560)

>99.99%

(15/15)

>99.99%

(9,560/(9,575-15))

 What does it mean for the pregnancy?

       

 The high IONA® PPV implies that the false positive results are minimised (unaffected fetus tested positive); meaning less unnecessary diagnostic procedures are required.

 The high IONA® NPV implies that the false negative results are minimised (affected fetus tested negative), meaning fewer syndromes are being missed. 


Observed performances are based on Post-Market Surveillance of the IONA® Nx test in over 9,575 singleton and monochorionic twin pregnancies, from a population of women who are predominantly at a higher risk of having a fetus with Down's syndrome. 

Performances are dependant of laboratories fully reporting discordant results to Yourgene Health Plc. From Data held on file by Yourgene Health. Correct as of 11th June.

 

Test performance observed following validation metrics for singleton and twin pregnancies

IONA® Nx validation studya
 SensitivitySpecificity
Trisomy 21

>99.99%
(46/46)
95% CI: 92.3 - 100%

>99.99% 
(426/426)
95% CI: 99.1 – 100%

Trisomy 18

>99.99%
(20/20)
95% CI: 83.2 – 100%

>99.99%
(452/452)
95% CI: 99.2 – 100%

Trisomy 13

>99.99%
(10/10)
95% CI: 69.2 – 100%

>99.99%
(462/462)
95% CI: 99.2 – 100%

a The Validation performance has been demonstrated by evaluating 472 clinical samples from singleton and twin pregnancy and comparing to a reference result of an amniocentesis or chorionic villus sampling (CVS) sample or a birth outcome.

 

Condition

Sensitivity

Specificity

XO
(Turner Syndrome)

>99.99%
(15/15)
95% CI: 78.2 – 100%

>99.99%
(428/428)
95% CI: 99.1 – 100%

XXY
(Klinefelter syndrome)

>99.99%
(4/4)
95% CI: 39.8 – 100%

99.5%
(437/439)
95% CI: 98.4 – 99.9%

XYY
(XYY Syndrome)

N/A

>99.99%
(443/443)
95% CI: 99.2 – 100%

XXX
(Trisomy X)

>99.99%
(1/1)
95% CI: 2.5 – 100%

>99.99%
(442/442)
95% CI: 99.2 – 100%

Trisomy

>99.9%
(3/3)
95% CI: 29.2 – 100%

99.3%
(439/442)
95% CI: 98.0 – 99.9%

Monosomy

N/A

>99.9%
(442/442)
95% CI: 99.2 – 100%

The Validation performance has been demonstrated by evaluating 443 clinical samples from singleton and comparing to a reference result of an amniocentesis or chorionic villus sampling (CVS) sample or a birth outcome.

This has been demonstrated using the IONA® Nx cfDNA Library Preparation DX kit and the IONA® analysis software version 2.0.2. Data held on file by Yourgene Health Plc.