Genomic imprinting, referring to an epigenetic marking resulting in monoallelic gene expression, plays a critical role in development. Recently, various imprinting diseases were reported in animals (Large Offspring syndrome (LOS)) and humans (Beckwith-Wiedemann syndrome (BWS) and Angelman syndrome (AS)) born after ART. In all cases, an imprinting defect was involved (loss of methylation at ICR2 in BWS, at SNRPN in AS and at IGF2R DMR2 in LOS). These data suggest that ART procedures may impair the establishment or the maintenance (following fertilization) of methylation marks at maternally imprinted loci. In view of these data, the aim of this study is to determine if children born following ART exhibit an increased risk of imprinting defects. If the answer is yes, the second objective is to identify the problematic step in the ART procedure and thus to suppress or modify this step.

Methodology: assessment of the methylation status at 9 different imprinted loci (using Southern blot and methyl-specific quantitative PCR) in 3 groups of patients: 150 children naturally conceived, 150 children conceived after ovarian stimulation but with in vivo fertilization, and 150 children conceived after ovarian stimulation and in VITRO fertilization. These analyses will be performed on cord blood. Fragments of placental tissue will also be collected for further analyses. Patients will be selected in maternity hospitals associated with ART departments ( ANTOINE BECLERE HOSPITAL, Cochin HOSPITAL, Saint-Vincent de Paul HOSPITAL, Jean VERDIER HOSPITAL, Tenon HOSPITAL and Dijon Hospital).

This work is also a unique opportunity to establish a DNA, RNA and tissue collection allowing further investigation regarding other epigenetic modifications than DNA methylation, not only at imprinted loci, but also in other genomic regions regulated by epigenetic modifications.

Inclusion Criteria:

Mother :

• Age: 26 to 40 at conception
• Single foetus pregnancy
• Signed informed consent
• Affiliation to French health benefits
• Absence of maternal pathology
• Normal foetal karyotype (if available)
• Known procedure of ovarian stimulation
• ART procedure without sperm or oocyte donation
• ART in a participating ART departments
• Delivery in a participating hospital

Father

• Age : 18 to 50 at conception
• Signed informed consent

Exclusion Criteria:

• Abnormal foetal karyotype (if available)
• Delivery before 35 weeks of amenorrhea
• Delivery in not participating hospital
• Delivery complication leading to the absence of sample collection

Women followed in a participating ART departments