Genetic variation in CCDC93 is associated with elevated central systolic blood pressure, impaired arterial relaxation, and mitochondrial dysfunction.

Genetic studies of blood pressure (BP) traits to date have been performed on conventional measures by brachial cuff sphygmomanometer for systolic BP (SBP) and diastolic BP, integrating several physiologic occurrences. Genetic associations with central SBP (cSBP) have not been well-studied. Genetic discovery studies of BP have been most often performed in European-ancestry samples. Here, we investigated genetic associations with cSBP in a Chinese population and functionally validated the impact of a novel associated coiled-coil domain containing 93 (CCDC93) gene on BP regulation. An exome-wide association study (EWAS) was performed using a mixed linear model of non-invasive cSBP and peripheral BP traits in a Han Chinese population (N = 5,954) from Beijing, China genotyped with a customized Illumina ExomeChip array. We identified four SNP-trait associations with three SNPs, including two novel associations (rs2165468-SBP and rs33975708-cSBP). rs33975708 is a coding variant in the CCDC93 gene, c.535C>T, p.Arg179Cys (MAF = 0.15%), and was associated with increased cSBP (β = 29.3 mmHg, P = 1.23x10-7). CRISPR/Cas9 genome editing was used to model the effect of Ccdc93 loss in mice. Homozygous Ccdc93 deletion was lethal prior to day 10.5 of embryonic development. Ccdc93+/- heterozygous mice were viable and morphologically normal, with 1.3-fold lower aortic Ccdc93 protein expression (P = 0.0041) and elevated SBP as compared to littermate Ccdc93+/+ controls (110±8 mmHg vs 125±10 mmHg, P = 0.016). Wire myography of Ccdc93+/- aortae showed impaired acetylcholine-induced relaxation and enhanced phenylephrine-induced contraction. RNA-Seq transcriptome analysis of Ccdc93+/- mouse thoracic aortae identified significantly enriched pathways altered in fatty acid metabolism and mitochondrial metabolism. Plasma free fatty acid levels were elevated in Ccdc93+/- mice (96±7mM vs 124±13mM, P = 0.0031) and aortic mitochondrial dysfunction was observed through aberrant Parkin and Nix protein expression. Together, our genetic and functional studies support a novel role of CCDC93 in the regulation of BP through its effects on vascular mitochondrial function and endothelial function. Author summary: More than 1000 loci have been reported in previous gene discovery efforts for blood pressure and hypertension. cSBP is a unique blood pressure trait that has not been as extensively studied as peripheral BP, and correlates of cSBP may provide a better indication of future cardiovascular events. In this study we replicated several BP associations in a Han Chinese cohort and found a novel association with a coding variant in CCDC93 (rs33975708, c.535C>T, p.Arg179Cys, MAF 0.15%) which was strongly associated with higher cSBP. To model loss of Ccdc93 and functionally validate the human genetic association, a new transgenic mouse was created. Ccdc93 homozygous deletion was embryonic lethal, and mice with heterozygous loss of Ccdc93 exhibited impaired arterial relaxation and enhanced contractile responses. Aortic RNA-seq analysis of Ccdc93+/- heterozygous mice identified metabolic dysregulation and mitochondrial dysfunction, which was validated by features of elevated plasma free fatty acids and increased aortic Parkin and Nix protein expression. Improved knowledge of the genes involved in BP regulation is needed to develop effective therapies to manage elevated BP, and this study identified the gene CCDC93 as a novel regulator of blood pressure and vascular function. [ABSTRACT FROM AUTHOR]