Genotype Expression and Phenotype of Endothelial Cells, Carrying an ACVRL1, ENG or SMAD4 Mutation, in Response to BMP9 for the Identification of New Therapeutic Targets in Hereditary Haemorrhagic Telangiectasia (CAERO)

Genotype Expression and Phenotype of Endothelial Cells, Carrying an ACVRL1, ENG or SMAD4 Mutation, in Response to BMP9 for the Identification of New Therapeutic Targets in Hereditary Haemorrhagic Telangiectasia

Genotype Expression and Phenotype of Endothelial Cells, Carrying an ACVRL1, ENG or SMAD4 Mutation, in Response to BMP9 for the Identification of New Therapeutic Targets in Hereditary Haemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu syndrome patients are carriers of a heterozygous mutation of the activin receptor-like kinase 1 (ACVRL1), Endoglin (ENG) or Mothers against decapentaplegic homolog 4 (SMAD4) gene. HHT involves the Bone Morphogenetic Protein 9 (BMP9)/Activin receptor-Like Kinase 1 (ALK1)-endoglin signalling pathway. BMP9 is a growth factor that binds to ALK1 receptor and to endoglin its co-receptors and physiologically activates Smad signaling pathway. Endothelial cells in HHT patients display half expression of functional ALK1 receptors or endoglin co-receptors or of the transcription factor SMAD4, which should lead to effects on the functions of these cells. The identification of differences in gene expression between endothelial cells from HHT patients and healthy donors will allow the identification of new functions or new target pathways for therapy. Circulating endothelial cells are rare in the bloodstream in adults, but are present in greater quantities in cord blood.

16 newborns with one parent suffering HHT disease and carrying a mutation in the ACVRL1, ENG or SMAD4 gene will be included in this study.

Collection of 2 milliliters (mL) of cord blood on an Ethylenediaminetetraacetic acid (EDTA) tube, on the day of delivery and after cutting the umbilical cord, for genetic testing

The primary outcome is the obtention of at least one clone of 10 000 cells from the cord blood after 3 weeks from the time of isolation. Number of viable cells is measured by Trypan blue test.

For the cord, the primary outcome is the obtention of 500 000 cells after one week from the isolation. Number of viable cells is measured by Trypan blue test.

After isolation and amplification, cells from cord or from clones from the cord blood are frozen in vials. The cells viability (50 to 70% of alive cells after thawing) is a criteria of successful experiment.

The third outcome is reached when we obtain up to 5 µg of RNA after cell seeding and stimulation with growth factors. Gene expression is measured by real-time polymerase chain reaction (RT-qPCR) and Ribonucleic acid Sequencing (RNAseq).

Inclusion Criteria: Newborn whose parents : are adults are affiliated to a social security or similar are not subject to any legal protection measures Newborn child with one parent who has monitored for HHT confirmed by molecular biology (carrier of a mutation of the SMAD4, ENG or ACVRL1 gene). Consent signed by the two representatives of parental authority Exclusion Criteria: One of the two parents opposes donating the umbilical cord blood and the umbilical cord for research One of the two parents opposes genetic testing Patient for whom it was not possible to obtain umbilical cord blood after delivery for technical or medical reasons.