Trio exome sequencing is highly relevant in prenatal diagnostics.

OBJECTIVE: About 3% of newborns show malformations, with about 20% of the affected having genetic causes. Clarification of genetic diseases in postnatal diagnostics was significantly improved with high-throughput sequencing, in particular through whole exome sequencing covering all protein-coding regions. Here, we aim to extend the use of this technology to prenatal diagnostics. METHOD: Between 07/2018 and 10/2020, 500 pregnancies with fetal ultrasound abnormalities were analyzed after genetic counseling as part of prenatal diagnostics using WES of the fetus and parents. RESULTS: Molecular genetic findings could explain ultrasound abnormalities in 38% of affected fetuses. In 47% of these, disease-causing de novo variants were found. Pathogenic variants in genes with autosomal recessive or X-linked inheritance were detected in more than one-third (70/189 = 37%). The latter are associated with increased probability of recurrence, making their detection important for further pregnancies. Average time from sample receipt to report was 12 days in the recent cases. CONCLUSION: Trio exome sequencing is a useful addition to prenatal diagnostics due to its high diagnostic yield and short processing time (comparable to chromosome analysis). It covers a wide spectrum of genetic changes. Comprehensive interdisciplinary counseling before and after diagnostics is indispensable.

HIC-5 is a novel repressor of lymphoid enhancer factor/T-cell factor-driven transcription.

Activation of Wnt/beta-catenin target genes is regulated by a heterodimer of beta-catenin and the high mobility group box transcription factors of the lymphoid enhancer factor (LEF)/T-cell factor (TCF) family. In vertebrates, four LEF/TCF family members have been identified. They all contain a conserved beta-catenin-binding motif at the N terminus and a highly conserved high mobility group box for DNA binding. The core sequence between these motifs is less conserved and contributes to the specific properties of the individual family members. To identify interacting proteins that allocate specific functions to the individual LEF/TCF transcription factors, we performed a yeast two-hybrid screen using the less conserved core sequence as bait. We isolated the murine LIM protein HIC-5 (hydrogen peroxide-induced clone 5; also termed ARA-55 (androgen receptor activator of 55 kDa)) and cloned the highly conserved Xenopus homolog. In addition, we report that the LIM domain-containing C-terminal half of HIC-5 binds to a conserved alternatively spliced exon in LEF/TCF transcription factors. Our functional analyses revealed that HIC-5 acts as negative regulator of a subset of LEF/TCF family members, which have been characterized as activators in reporter gene analyses and in the Xenopus axis induction assay. In addition, we observed a repressive interference of LEF/TCF family members with HIC-5-mediated activation of glucocorticoid-driven transcription, which again could be allocated to specific LEF/TCF subtypes. With the characterization of HIC-5 as a binding partner of the alternatively spliced exon in LEF/TCF transcription factors, we identified a novel molecular mechanism in the dialog of steroid and canonical Wnt signaling that is LEF/TCF subtype-dependent.