A multi-trait GWAS identifies novel genes influencing albuminuria.

BACKGROUND: Albuminuria is common and associated with increased risks of end-stage kidney disease and cardiovascular diseases, yet its underlying mechanism remains obscure. Previous genome-wide association studies (GWAS) for albuminuria did not consider gene pleiotropy and primarily focused on European ancestry populations. This study adopted a multi-trait analysis of GWAS (MTAG) approach to jointly analyze two vital kidney traits, estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) to identify and prioritize the genes associated with UACR. METHODS: Data from the Taiwan Biobank from 2012 to 2023 were analyzed. GWAS of UACR and eGFR were performed separately and the summary statistics from these GWAS were jointly analyzed using MTAG. The polygenic risk scores (PRS) of UACR were constructed for validation. The UACR-associated loci were further fine-mapped and prioritized based on their deleteriousness, eQTL associations, and relatedness to Mendelian kidney diseases. RESULTS: MTAG analysis of the UACR revealed 15 genetic loci, including 12 novel loci. The PRS for UACR was significantly associated with urinary albumin level (P < 0.001) and microalbuminuria (P = 0.001 ∼ 0.045). A list of priority genes was generated. Twelve genes with high priority included the albumin endocytic receptor gene LRP2 and ciliary genes  IFT172. CONCLUSIONS: The findings of this multi-trait GWAS suggest that primary cilia play a role in sensing mechanical stimuli, leading to albumin endocytosis. The priority list of genes warrants further translational investigation to reduce albuminuria.

Validation of human telomere length multi-ancestry meta-analysis association signals identifies POP5 and KBTBD6 as human telomere length regulation genes.

Genome-wide association studies (GWAS) have become well-powered to detect loci associated with telomere length. However, no prior work has validated genes nominated by GWAS to examine their role in telomere length regulation. We conducted a multi-ancestry meta-analysis of 211,369 individuals and identified five novel association signals. Enrichment analyses of chromatin state and cell-type heritability suggested that blood/immune cells are the most relevant cell type to examine telomere length association signals. We validated specific GWAS associations by overexpressing KBTBD6 or POP5 and demonstrated that both lengthened telomeres. CRISPR/Cas9 deletion of the predicted causal regions in K562 blood cells reduced expression of these genes, demonstrating that these loci are related to transcriptional regulation of KBTBD6 and POP5. Our results demonstrate the utility of telomere length GWAS in the identification of telomere length regulation mechanisms and validate KBTBD6 and POP5 as genes affecting telomere length regulation.

Association of exosomes in patients with compromised myocardial perfusion on functional imaging.

OBJECTIVES: Exosomes are membrane vesicles that are actively secreted in response to microenvironmental stimuli. In this study, we quantified the amount of exosomes in patients with significant coronary artery disease (CAD) and evaluated its relationship with myocardial perfusion imaging (MPI) results. METHODS: Patients who underwent both MPI and coronary angiography were recruited. Plasma was collected during angiography, and exosomes were extracted via the precipitation method. The summed stress scores (SSS), summed difference scores, and ventricular functional parameters were calculated from the MPI and compared with the amounts of exosomes and extracted miRNAs. RESULTS: In total, 115 patients were enrolled (males: 78 %; mean age: 66.6 ± 10.6 years). Those with abnormal SSS according to the MPI had significantly fewer exosomes (p = 0.032). After multivariate analysis, the SSS remained significantly related to the amount of exosomes (p = 0.035). In forty randomly selected samples, miRNA-432-5p and miRNA-382-3p were upregulated in patients with abnormal SSS. CONCLUSIONS: Patients with compromised poststress myocardial perfusion on MPI tended to have fewer exosomes in association with CAD-related miRNAs. This is the first study to clarify the fundamental and pathophysiological causes of CAD using radiographic examinations.