Complete lung agenesis caused by complex genomic rearrangements with neo-TAD formation at the SHH locus.

During human organogenesis, lung development is a timely and tightly regulated developmental process under the control of a large number of signaling molecules. Understanding how genetic variants can disturb normal lung development causing different lung malformations is a major goal for dissecting molecular mechanisms during embryogenesis. Here, through exome sequencing (ES), array CGH, genome sequencing (GS) and Hi-C, we aimed at elucidating the molecular basis of bilateral isolated lung agenesis in three fetuses born to a non-consanguineous family. We detected a complex genomic rearrangement containing duplicated, triplicated and deleted fragments involving the SHH locus in fetuses presenting complete agenesis of both lungs and near-complete agenesis of the trachea, diagnosed by ultrasound screening and confirmed at autopsy following termination. The rearrangement did not include SHH itself, but several regulatory elements for lung development, such as MACS1, a major SHH lung enhancer, and the neighboring genes MNX1 and NOM1. The rearrangement incorporated parts of two topologically associating domains (TADs) including their boundaries. Hi-C of cells from one of the affected fetuses showed the formation of two novel TADs each containing SHH enhancers and the MNX1 and NOM1 genes. Hi-C together with GS indicate that the new 3D conformation is likely causative for this condition by an inappropriate activation of MNX1 included in the neo-TADs by MACS1 enhancer, further highlighting the importance of the 3D chromatin conformation in human disease.

13q31.1 microdeletion: A prenatal case report with macrocephaly and macroglossia.

We report on a female fetus with macrocephaly and macroglossia harbouring 13q31.1 microdeletion encompassing three genes: SPRY2, NDFIP2 and RBM26. NDFIP2 protein is involved in ubiquitination and in Ras/mitogen-activated protein kinase (MAPK) signaling pathways. SPRY2 protein is part of Sprout protein family and inhibits the Ras/MAPK pathways. Ras/MAPK pathway plays important role in complex cellular programs including cell differentiation and proliferation. Germline mutations in genes encoding protein involved in the MAPK cascade is responsible for a wide family of developmental disorders known as RASopathies. Some RASopathies, such as Costello syndrome, present a phenotype with (relative) macrocephaly as perinatal features. However, prenatal-onset macroglossia are generally absent in this syndrome but rather suggestive of the Beckwith-Wiedemann syndrome for which molecular testing were negative. Phenotype-genotype correlation with patients from DECIPHER defines NDFIP2 and SPRY2 as a possible candidate genes for a RASopathy potentially responsible for the clinical features in the fetus. Finally, this original case of 13q31.1 microdeletion underlines the importance of array-CGH in prenatal diagnosis with sonographic signs such as macroglossia and/or macrocephaly. In this case, genetic investigation should be not limited to the search of well-known genetic causes and other genomic microdeletions should be considered as alternative diagnoses for macroglossia.

Fetal anemia as a signal of congenital syphilis.

An upsurge in syphilis has been observed almost everywhere over the past decade. The mother's clinical presentation is often uninformative. The diagnosis of maternal syphilis infection is most often based on serologic tests that allow early Extencilline treatment. Syphilis ultrasound findings are non-specific, and delay before treatment can be decisive for prognosis. Fetal anemia is a physiological consequence of severe infection. We confirmed that syphilis can be suggested non-invasively by MCA-PSV measurements in a context of ascitis or atypical hydrops in the absence of usual causes. It is therefore important to perform maternal TPHA/VDRL serology if fetal anemia is suspected. In association with Extencilline treatment, intra uterine transfusion can limit consequences of infection. Reduced fetal movements and non-reactive fetal heart rate may prefigure acute perinatal complications or stillbirth.

Contribution of 3D ultrasound and fetal face studies to the prenatal diagnosis of Pallister-Killian syndrome.

BACKGROUND: Pallister-Killian syndrome (PKS) is a multiple malformation syndrome caused by a chromosomal abnormality in which the presence of four copies of the short arm of chromosome 12 results in severe mental retardation. Cytogenetic diagnosis is particularly difficult due to the specific tissue distribution of the abnormality. PKS may be suspected based on the prenatal ultrasound detection of polyhydramnios and diaphragmatic hernia, possibly associated with rhizomelic micromelia. METHOD AND RESULTS: We report here a case of PKS in which the 3D ultrasound examination of facial features after prenatal PKS diagnosis showed signs suggestive of the syndrome. CONCLUSION: A detailed 3D examination of the fetal face may help to guide diagnosis, particularly when the only sign detected on ultrasound is polyhydramnios, as in the case reported here.