Congenital Malformation, Rare Fetal Genetic Diseases
Conditions
Keywords
Congenital malformation, DNA methylation abnormalities, Episignature, CHD7 gene, KMT2D gene, HYLS1 gene, TCTN3 gene, FLVCR2 gene, CHARGE syndrome, KABUKI syndrome
Brief summary
It is necessary to define reference DNA Methylation Episignatures from fetal DNA. The hypotheses are: * It is possible to define reference DNA Methylation Episignatures from fetal DNA extracted from amniotic fluid or frozen tissues collected during the postmortem examination * Fetal DNA Methylation Episignatures may be different to postanal DNA Methylation Episignatures defined on DNA extracted from blood
Detailed description
Congenital anomalies (CA) complicate 3 to 5% of pregnancies and may be associated with genetic disorders. Diagnosis of genetic diseases is a major medical challenge, especially during pregnancy. Over the past two decades, next-generation sequencing (NGS) has revolutionized our ability to identify the genetic condition associated with CA. During pregnancy, prenatal exome sequencing identified an additional diagnosis in around 30% of fetuses with CA when standard chromosomal investigations (karyotype and chromosomal microarray analysis, CMA) fail to provide a diagnosis. Despite these major advances, around 40% of rare diseases remain unsolved, including 10-15% of patients harboring variants of uncertain significance (VUS). After birth, additional functional analyses ("multi-OMICS"), including genome-wide DNA methylation studies, may be offered to reclassify VUS. DNA methylation anomalies play an important role in pathologies (developmental disorders and oncology). DNA methylation Episignatures, defined as the cumulative DNA methylation patterns occurring at multiple CpG dinucleotides across the genome, have been recognized to be intricately associated with many human traits, including age, sex, and disease status. Recently, DNA Methylation Episignatures have been identified in the blood of children or adults for several well-characterized genetic diseases. However, these postnatal DNA Methylation Episignatures cannot be used during pregnancy, because DNA methylation changes from one tissue to another and during time, especially during fetal developpement. In addition, the tissues available during pregnancy are different from those analyzed postnatally (blood).
Interventions
GENETICMethylation analysis
Genomic DNA will be treated with bisulfite. 500 ng of processed DNA is then hybrized on an EPICv2 array Infinium methylation (Illumina, San Diego, CA, USA). This microarray enables the analysis of approximately 865 000 methylation sites at promoters, enhancers, CpG islands, intergenic and intragenic regions. It is the most widely used chip in the literature, including almost all of the EPIGENETIC SIGNATURES reported in human pathology.
Sponsors
Assistance Publique - Hôpitaux de Paris
URC-CIC Paris Descartes Necker Cochin
Study design
Observational model
OTHER
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
0 Years to 18 Years
Healthy volunteers
Yes
Inclusion criteria
* Patient Inclusion Criteria: * Fetuses with a postmortem examination as part of the etiological diagnosis of developmental abnormality within the Genomic Medicine of Rare Diseases department of the Necker Children's Hospital, and whose DNA extracted from lung and amniotic fluid is available * OR a child cared for in the Genomic Medicine for Rare Diseases department of the Necker Children's Hospital, and whose DNA extracted from whole blood is available * with pathogenic or probably pathogenic variation in a gene following CHD7, KMT2D, HYLS1, TCTN3 or FLVCR2 * whose parents have consented to molecular genetic testing as part of diagnosis and research * Negative Controls : * Fetuses with a postmortem examination as part of the etiological diagnosis of developmental abnormality within the Genomic Medicine of Rare Diseases department of the Necker Children's Hospital, and whose DNA extracted from lung and amniotic fluid are available * OR a child cared for in the Genomic Medicine for Rare Diseases department of the Necker Children's Hospital, and whose DNA extracted from whole blood is available * does not have pathogenic or probably pathogenic variation in a gene following CHD7, KMT2D, HYLS1, TCTN3 or FLVCR2 * whose parents have consented to molecular genetic testing as part of diagnosis and research * For everyone: • For living participants: Non-objection by holders of parental authority to the reuse of clinical data and biological samples collected and stored in the context of care (consent of care). • For deceased participants: * Consent of the holders of parental authority to the use of the samples kept for research purposes, signed as part of the treatment * No mention of opposition to the reuse of clinical data from the treatment in the patient's medical record
Exclusion criteria
* Refusal of postmortem examination in case of fetal loss * Parents' refusal of molecular investigations
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Epigenetic signature associated with pathogenic variations in the CHD7 gene (CHARGE Syndrome) | 12 months | Evidence of epigenetic signature from fetal tissue DNA in fetuses with pathogenic or probably pathogenic variation |
| Epigenetic signature associated with pathogenic variations in the KMT2D gene (KABUKI syndrome) | 12 months | Evidence of epigenetic signature from fetal tissue DNA in fetuses with pathogenic or probably pathogenic variation |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Differential methylation between fetal and postnatal epigenetic signature | 12 months | Evidence of differential methylation between fetal an postnatal epigenetic signature |
| Differential methylation between tissue and amniotic fluid epigenetic signatures | 12 months | Evidence of differential methylation between tissue and amniotic fluid epigenetic signatures |
| Statistical prediction parameter for each epigenetic signature | 12 months | Measurement of the statistical prediction parameter for each epigenetic signature |
| Identification of a new epigenetic signature in foetal pathologies | 12 months | Identification of news epigenetic signatures of exclusively pathologies associated with the HYLS1, TCTN3 and FLVCR2 genes |
Countries
France
Contacts
CONTACTNicolas BOURGON, MD, PhD
CONTACTNelly BRIAND, PhD
STUDY_DIRECTORManon TESSIER, MD, PhD
Assistance Publique - Hôpitaux de Paris
Outcome results
None listed