Prenatal Molecular Characterisation by CGH+SNP-ARRAY of Supernumerary Marker Chromosomes and de Novo Apparently Balanced Reciprocal Translocations

In the prenatal period, les supernumerary marker chromosomes (SMC) and de novo apparently balanced reciprocal translocations are revealed by foetal karyotyping, which does not always make it possible to determine whether the anomaly is balanced or not and does not reveal uniparental disomy. The presence of these chromosomal rearrangements raises a difficult question for genetic counselling during pregnancy because of the risk of intellectual deficiency in the foetus. CGH+SNP-Array can provide information concerning 1) the balanced or not nature of these translocations 2) the presence or not of euchromatin in the SMC 3) the presence or not of uniparental disomy.

Inclusion Criteria:

• Metaphase karyotyping with SMC or a de novo Apparently-balanced reciprocal translocation
• Parents covered by the National Health Insurance Agency,
• Consent of the parents

Exclusion Criteria:

• Persons not covered by the National Health Insurance Agency
• Normal foetal karyotyping or showing chromosomal anomalies not related to the present study (trisomy 18….) or inherited anomalies
• Absence of a sample from one of the parents