Trans-ethnic Fine Mapping Highlights Kidney-Function Genes Linked to Salt Sensitivity

The UMOD Locus: Insights into the Pathogenesis and Prognosis of Kidney Disease

The identification of genetic factors associated with kidney disease has the potential to provide critical insights into disease mechanisms. Genome-wide association studies have uncovered genomic regions associated with renal function metrics and risk of CKD. UMOD is among the most outstanding loci associated with CKD in the general population, because it has a large effect on eGFR and CKD risk that is consistent across different ethnic groups. The relevance of UMOD for CKD is clear, because the encoded protein, uromodulin (Tamm-Horsfall protein), is exclusively produced by the kidney tubule and has specific biochemical properties that mediate important functions in the kidney and urine. Rare mutations in UMOD are the major cause of autosomal dominant tubulointerstitial kidney disease, a condition that leads to CKD and ESRD. In this brief review, we use the UMOD paradigm to describe how population genetic studies can yield insight into the pathogenesis and prognosis of kidney diseases.

Systematical analyses of variants in DNase I hypersensitive sites to identify hepatocellular carcinoma susceptibility loci in a Chinese population

BACKGROUND AND AIM

Although several variants located at coding and non-coding regions were evaluated by previous studies, the evidence for associations between variants located in DNase I-hypersensitive sites (DHSs) and hepatocellular carcinoma (HCC) risk was still limited. Recent advances using ENCODE data indicated that genetic variants in DHSs played an important role in carcinogenesis. Therefore, systematically investigating the associations between regulatory variants in DHSs and HCC risk should be put on the agenda.

METHODS

We conducted a case-control design (1538 HCC cases vs 1465 normal controls) to evaluate the effects on HCC for the variants located at the uniform DNase I hypersensitive sites sequencing peaks in a Chinese population.

RESULTS

We found two novel single nucleotide polymorphisms rs12309362 (odds ratio = 0.64, P = 5.61 × 10^-6 ) and rs9970827 (odds ratio = 0.73, P = 7.23 × 10^-6 ) significantly associated with decreased risk of HCC. Conditional analysis proved that both of them independently contributed to the susceptibility of HCC. Expression quantitative trait loci analysis found that A allele of rs12309362 was significantly associated with an elevated expression of phosphatase phosphoglycerate mutase 5 in liver tissues. In addition, gene-based analysis indicated that CEBPB (P = 1 × 10^-4 ) was associated with the risk of HCC, and the expression of CEBPB was significantly lower in 50 The Cancer Genome Atlas HCC tumor tissues compared with matched normal tissues.

CONCLUSIONS

Our results indicated that rs12309362 (G > A), rs9970827 (A > G) in DHSs, and elevated expression of CEBPB were associated with a decreased risk of HCC. These results may contribute us to understand the function of regulatory DNA sequences in HCC development.

Uromodulin: from physiology to rare and complex kidney disorders

Uromodulin (also known as Tamm-Horsfall protein) is exclusively produced in the kidney and is the most abundant protein in normal urine. The function of uromodulin remains elusive, but the available data suggest that this protein might regulate salt transport, protect against urinary tract infection and kidney stones, and have roles in kidney injury and innate immunity. Interest in uromodulin was boosted by genetic studies that reported involvement of the UMOD gene, which encodes uromodulin, in a spectrum of rare and common kidney diseases. Rare mutations in UMOD cause autosomal dominant tubulointerstitial kidney disease (ADTKD), which leads to chronic kidney disease (CKD). Moreover, genome-wide association studies have identified common variants in UMOD that are strongly associated with risk of CKD and also with hypertension and kidney stones in the general population. These findings have opened up a new field of kidney research. In this Review we summarize biochemical, physiological, genetic and pathological insights into the roles of uromodulin; the mechanisms by which UMOD mutations cause ADTKD, and the association of common UMOD variants with complex disorders.