Retrospective Study Using Next Generation Sequencing (NGS) on Biological Samples to Improve Genetic Counseling for Patients With Previously Explored Craniofacial Midline Defects.

Holoprosencephaly, or HPE, is the most common congenital cerebral malformation in humans and the most severe of a group of pathologies related to a deficiency of the SHH signalling pathway (Sonic Hedgehog SHH-D). It is characterized by severe cerebral and craniofacial abnormalities. The regulation of SHH concentration is therefore crucial for correct craniofacial development. Despite the recent identification of about 20 genes, 70% of cases of EHPE and craniofacial midline abnormalities of genetic origin do not have a molecular diagnosis. It is therefore important to continue the search for new candidate genes to improve the understanding of brain and facial development and to improve genetic counseling for these families. The development of Next-Generation Sequencing (NGS) technologies opens up the possibility of studying the exome or even the genome in a single manipulation. The latter type of analysis is particularly well suited to the discovery of new genes and will therefore improve the care of patients and their families.