Metatranscriptomic Next Generation Sequencing in First Trimester Trophoblast With Increased Fetal Nuchal Translucency (METAHCN)

Study Overview
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Brief Summary
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The study is based on the hypothesis that increased nuchal translucency may be associated with a materno fetal infection and that the pathogen responsible for this infection could be identify with metatranscriptomic next-generation sequencing in the trophoblast tissue.

Detailed Description
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Nuchal translucency > 3.5 mm in the first trimester of pregnancy is due to fluid accumulation in the subcutaneous tissue in the nuchal area. This is seen in around 1% of all pregnancies. Increased nuchal translucency is explained by a chromosomic abnormality (mainly Down syndrome) in 30 to 40% of cases. Therefore, the state of the art is to perform an array CGH on chorionic villi sampling. Cases of nuchal translucency that are not explained by a chromosomic abnormality may be associated: with fetal defect (heart, congenital diaphragmatic hernia) in 10% of cases, with genetic disease in 4% of cases or with miscarriage or fetal death of unknown etiology in 18% of cases. The etiology of increased nuchal translucency remains unknown in more than 50% of the cases. It could be linked to inflammation or reflect an infection but this latter association has been rarely studied. This association was suggested in a study reporting serology of CMV, toxoplasmosis or B19 parvovirus primary infections in pregnant women carrying a fetus with increased nuchal translucency. In those rare cases, the microorganism was not searched directly in the trophoblast tissue. In the investigators' center, the investigators describe in a context of maternal primary infection, one case of increased nuchal translucency with a positive CMV PCR in the trophoblast tissue collected at 12 weeks. Other pathogens yet not identified might be associated with increased nuchal translucency. Metatranscriptomic next generation sequencing (mNGS) allows to search for any pathogens without a priori. It is therefore a powerful technic to study this potential association between increased nuchal translucency and infection.

Official Title
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Pathogen Detection by Metatranscriptomic Next Generation Sequencing in the Trophoblast Collected in Women Carrying a Fetus With Increasing Nuchal Translucency in the First Trimester of Pregnancy

Conditions
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Increased Nuchal Translucency in the First Trimester of Pregnancy

Intervention / Treatment
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* Biological: Metatranscriptomic
* Diagnostic Test: Specific microbiologic diagnosis


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pregnant women Singleton pregnancy First trimester (11 GA+0D to 13 GA+6D) Carrying a fetus with a nuchal translucency > 3.5 mm for which a chorionic villi sampling is performed OR a suspicion of genetic abnormalities for which a chorionic villi sampling is performed Delivery planned at Necker hospital Not opposed to participation Exclusion Criteria Age <18 years no health insurance difficulties in understanding the French language chronic infection (HIV, HBV, HVC and HTLV-1)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Nuchal translucency with no genetic abnormalities<br>Pregnant women between 11 and 14 weeks with a fetus showing a nuchal translucency > 3.5 mm and no genetic abnormalities with array CGH. | Biological: Metatranscriptomic<br>* Analysis with metatranscriptomic next generation sequencing of trophoblast obtained by chorionic villi sampling<br>Diagnostic Test: Specific microbiologic diagnosis<br>* If a microorganism is detected by metatranscriptomic NGS, specific diagnosis (PCR and serology) will be done in maternal and neonatal samples (blood, urine, saliva)<br>|
| Nuchal translucency with genetic abnormalities<br>Pregnant women between 11 and 14 weeks with a fetus showing a nuchal translucency > 3.5 mm and a genetic abnormalities at array CGH. | Biological: Metatranscriptomic<br>* Analysis with metatranscriptomic next generation sequencing of trophoblast obtained by chorionic villi sampling<br>Diagnostic Test: Specific microbiologic diagnosis<br>* If a microorganism is detected by metatranscriptomic NGS, specific diagnosis (PCR and serology) will be done in maternal and neonatal samples (blood, urine, saliva)<br>|
| Genetic abnormalities<br>Pregnant women between 11 and 14 weeks with a fetus showing a nuchal translucency < 3.5 mm and a suspicion of genetic abnormalities | Biological: Metatranscriptomic<br>* Analysis with metatranscriptomic next generation sequencing of trophoblast obtained by chorionic villi sampling<br>Diagnostic Test: Specific microbiologic diagnosis<br>* If a microorganism is detected by metatranscriptomic NGS, specific diagnosis (PCR and serology) will be done in maternal and neonatal samples (blood, urine, saliva)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| microorganisms (viruses, bacteria, or parasites) in trophoblast samples | Identification by metatranscriptomic NGS, from women carrying a fetus with nuchal translucency (group 1) and in controls (group 2 and 3) | At inclusion, 11-14 weeks of pregnancy | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Miscarriage | Comparison in group 1 of the proportion of miscarriageaccording to the presence or not of a microorganism in the trophoblast. | at termination of pregnancy (assessed up to 7 months) | 
| intrauterine death | Comparison in group 1 of the proportion of intrauterine death according to the presence or not of a microorganism in the trophoblast. | at termination of pregnancy (assessed up to 7 months) | 
| fetal abnormalities | Comparison in group 1 of the proportion of fetal abnormalities, according to the presence or not of a microorganism in the trophoblast. | at delivery | 
| Gestational age | Comparison in group 1 of gestational age at birth, according to the presence or not of a microorganism in the trophoblast. | at delivery | 
| birth weight | Comparison in group 1 of birth weight, according to the presence or not of a microorganism in the trophoblast. | at delivery | 
| Detection of the microorganism identified by metatranscriptomic NGS by conventional diagnostic method in maternal samples | Amplification by real time PCR of the microorganism identified by metatranscriptomic NGS in maternal blood, urine, saliva and amniotic fluid if available | at inclusion | 
| Detection of the microorganism identified by metatranscriptomic NGS by conventional diagnostic method in maternal samples | specific serology to identify a maternal primary infection with the microorganism detected by metatranscriptomic NGS | at inclusion | 
| Detection of the microorganism identified by metatranscriptomic NGS by conventional diagnostic method in neonatal samples | Amplification by real time PCR of the microorganism identified by metatranscriptomic NGS in neonatal blood, urine, saliva | 3 days after birth | 
| Detection of the microorganism identified by metatranscriptomic NGS by conventional diagnostic method in neonatal samples | specific serology to identify a maternal primary infection with the microorganism detected by metatranscriptomic NGS | 3 days after birth | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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metatranscriptomic, next generation sequencing, metagenomic, trophoblast, high throughput sequencing, nuchal translucency