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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


(Detection or True Positive Rate)

 False Negative Rate (FNR)

 Specificity (True Negative Rate)

False Positive Rate (FPR) 

 Positive predictive value (PPV)


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

(201 / 9,575)













 Trisomy 18 

Edwards' syndrome

(61 / 9,575)













Trisomy 13

Patau's syndrome

(15 / 9,575)






(9,560, 9,560)







 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 2021.

Click here for IONA® Nx Clinical Validation data.