Novel Protein-Protein Interactions Highlighting the Crosstalk between Hypoplastic Left Heart Syndrome, Ciliopathies and Neurodevelopmental Delays

The Role of Cilia and the Complex Genetics of Congenital Heart Disease

Congenital heart disease (CHD) can affect up to 1% of live births, and despite abundant evidence of a genetic etiology, the genetic landscape of CHD is still not well understood. A large-scale mouse chemical mutagenesis screen for mutations causing CHD yielded a preponderance of cilia-related genes, pointing to a central role for cilia in CHD pathogenesis. The genes uncovered by the screen included genes that regulate ciliogenesis and cilia-transduced cell signaling as well as many that mediate endocytic trafficking, a cell process critical for both ciliogenesis and cell signaling. The clinical relevance of these findings is supported by whole-exome sequencing analysis of CHD patients that showed enrichment for pathogenic variants in ciliome genes. Surprisingly, among the ciliome CHD genes recovered were many that encoded direct protein-protein interactors. Assembly of the CHD genes into a protein-protein interaction network yielded a tight interactome that suggested this protein-protein interaction may have functional importance and that its disruption could contribute to the pathogenesis of CHD. In light of these and other findings, we propose that an interactome enriched for ciliome genes may provide the genomic context for the complex genetics of CHD and its often-observed incomplete penetrance and variable expressivity.

A novel chromosome 2q24.3-q32.1 microdeletion in a fetus with multiple malformations

BACKGROUND

Terminal or interstitial deletion of chromosome 2q is rarely reported but clinically significant, which can result in developmental malformations and psychomotor retardation in humans. In the present study, we analyzed this deletion to comprehensively clarify the relationship between phenotype and microdeletion region.

METHODS

We collected clinical records of the fetus and summarized patient symptoms. Subsequently, genomic DNA was extracted from fetal tissue or peripheral blood collected from parents. In addition, whole-exome sequencing (WES) and copy number variation sequencing (CNV-seq) were performed.

RESULTS

The fetus presented a previously unreported interstitial deletion of 2q24.3-q32.1. WES and CNV-seq revealed a de novo 18.46 Mb deletion at 2q24.3-q32.1, a region involving 94 protein-coding genes, including HOXD13, MAP3K20, DLX1, DLX2, SCN2A, and SCN1A. The fetus had upper and lower limb malformations, including camptodactyly and syndactyly, along with congenital cardiac defects.

CONCLUSION

Herein, we report a fetus with a novel microdeletion of chromosome 2q24.3-q32.1, likely a heterozygous pathogenic variant. Haploinsufficiency of HOXD13 might be related to limb deformity in the fetus.