Roderick Yao

Background: Elastin insufficiency causes recurrent vascular stenoses. Hemizygous deletion of the elastin gene ( ELN ) causes Williams-Beuren syndrome (WBS), while single nucleotide variants in ELN cause nonsyndromic supravalvar aortic stenosis (SVAS). Our objective was to compare cardiovascular disease outcomes in patients with WBS and nonsyndromic SVAS. Methods: Patients (81 WBS, 42 nonsyndromic SVAS) with cardiovascular disease were included in this retrospective single center study. Freedom from surgical and catheter interventions and reinterventions was compared. Vascular tissue from 8 patients and 6 controls was analyzed for arterial wall architecture. Results: Patients with nonsyndromic SVAS presented at a younger age (median 0.3 [0.4–0.7] years) compared with patients with WBS (1.3 [0.2–3.0] years) and had lower freedom from surgical/catheter interventions compared with patients with WBS, with median event-free survival 1.1 (0.3–5.9) versus 4.7 (2.4–13.3) years, respectively (hazard ratio, 1.62 [95% CI, 1.02–2.56]; P =0.04). Patients with nonsyndromic SVAS also had a lower freedom from reinterventions ( P =0.054 by log-rank test). This was related in part to a higher frequency of primary and reinterventions for concomitant valvar aortic stenosis. Histology revealed abnormal intimal and medial thickening, disorganized and fragmented elastic fibers, reduced smooth muscle calponin expression, and increased macrophage marker, CD68, expression in the arterial walls in patients with WBS and nonsyndromic SVAS compared with controls. Conclusions: Patients with nonsyndromic SVAS require early and more frequent vascular and valvular interventions and reinterventions, in particular for concomitant valvar aortic stenosis compared with patients with WBS. This provides important prognostic information to guide counseling of affected families with cardiovascular disease and may guide primary intervention strategies based on predicted risk of restenosis.

Cardiomyopathy (CMP) is a heritable genetic disorder. Protein-coding variants account for 20-30% of cases. The contribution of variants in non-coding DNA elements that regulate gene expression has not been explored. We performed whole-genome sequencing (WGS) of 228 unrelated CMP families. Besides pathogenic protein-coding variants in known CMP genes, 5% cases harbored rare loss-of-function variants in novel cardiac genes, with NRAP and FHOD3 being strong candidates. WGS also revealed a high burden of high-risk variants in promoters and enhancers of CMP genes in an additional 20% cases (Odds ratio 2.14, 95% CI 1.60-2.86, p=5.26×10 ⁻⁷ vs 1326 controls) with genes involved in α-dystroglycan glycosylation ( FKTN, DTNA ) and desmosomal signaling ( DSC2, DSG2 ) specifically enriched for regulatory variants (False discovery rate <0.03). These findings were independently replicated in the Genomics England CMP cohort (n=1266). The functional effect of non-coding variants on transcription was functionally validated in patient myocardium and reporter assays in human cardiomyocytes, and that of novel gene variants in zebrafish knockouts. Our results show that functionally active variants in novel genes and in regulatory elements of CMP genes contribute strongly to the genomic etiology of childhood-onset CMP.

Whole-genome sequencing (WGS) is becoming an increasingly important tool for detecting genomic variation. Blood derived DNA is the current standard for WGS for research or clinical purposes. We compared the level of microbial contamination, sequencing coverage, as well as yield and concordance of single-nucleotide polymorphism (SNP) and copy number variant (CNV) calls in WGS from paired blood and saliva samples from 5 pediatric heart disease patients. We found that although saliva samples contained a higher proportion of sequence reads that map to the human oral microbiome, these reads were readily excluded by mapping the reads to the human reference genome. Sequencing coverage was low only in 1 of 5 saliva samples. Over 95% SNPs (including rare SNPs) but <80% CNVs called in blood genomes were detected in paired saliva genomes. These findings suggest that most good quality saliva samples can serve as an alternative to blood samples for detection of sequence variants from WGS in cardiovascular disease patients.