Prevalence and characteristics of genetic disease in adult kidney stone formers

Role of Genetic Testing in Kidney Stone Disease: A Narrative Review

PURPOSE OF REVIEW

Kidney stone disease (KSD) is a common and potentially life-threatening condition, and half of patients experience a repeat kidney stone episode within 5-10 years. Despite the ~50% estimate heritability of KSD, international guidelines have not kept up with the pace of discovery of genetic causes of KSD. The European Association of Urology guidelines lists 7 genetic causes of KSD as 'high risk'.

RECENT FINDINGS

There are currently 46 known monogenic (single gene) causes of kidney stone disease, with evidence of association in a further 23 genes. There is also evidence for polygenic risk of developing KSD. Evidence is lacking for recurrent disease, and only one genome wide association study has investigated this phenomenon, identifying two associated genes (SLC34A1 and TRPV5). However, in the absence of other evidence, patients with genetic predisposition to KSD should be treated as 'high risk'. Further studies are needed to characterize both monogenic and polygenic associations with recurrent disease, to allow for appropriate risk stratification. Durability of test result must be balanced against cost. This would enable retrospective analysis if no genetic cause was found initially. We recommend genetic testing using a gene panel for all children, adults < 25 years, and older patients who have factors associated with high risk disease within the context of a wider metabolic evaluation. Those with a genetic predisposition should be managed via a multi-disciplinary team approach including urologists, radiologists, nephrologists, clinical geneticists and chemical pathologists. This will enable appropriate follow-up, counselling and potentially prophylaxis.

Paracellular Transport and Renal Tubule Calcium Handling: Emerging Roles in Kidney Stone Disease

The kidney plays a major role in maintenance of serum calcium concentration, which must be kept within a narrow range to avoid disruption of numerous physiologic processes that depend critically on the level of extracellular calcium, including cell signaling, bone structure, and muscle and nerve function. This defense of systemic calcium homeostasis comes, however, at the expense of the dumping of calcium into the kidney tissue and urine. Because of the large size and multivalency of the calcium ion, its salts are the least soluble among all the major cations in the body. The potential pathologic consequences of this are nephrocalcinosis and kidney stone disease. In this review, we discuss recent advances that have highlighted critical roles for the proximal tubule and thick ascending limb in renal calcium reabsorption, elucidated the molecular mechanisms for paracellular transport in these segments, and implicated disturbances in these processes in human disease.

Association between cardiometabolic index and kidney stones in US diabetic patients: NHANES 2007-2018

BACKGROUND

The cardiometabolic index (CMI), encompassing obesity and lipid metrics, is potentially linked to kidney stone prevalence in diabetic patients. However, studies on this association are sparse. This research evaluates CMI's impact on kidney stone occurrence in this group.

METHODS

Utilizing data from the 2007-2018 National Health and Nutrition Examination Survey, we explored the relationship between CMI and kidney stones in diabetic patients through multivariate logistic regression, generalized additive models, and smoothed curve fitting. Robustness checks included subgroup analyses and propensity score matching (PSM).

RESULTS

This study comprised 2714 participants in total, where the prevalence of kidney stones was found to be 16.82%. Using weighted multivariate logistic regression and fully adjusted models, it was revealed that elevated CMI levels are positively associated with an increased likelihood of developing kidney stones (OR = 1.17, 95% CI: 1.06, 1.30). Smooth curve fitting demonstrated that there was no non-linear relationship between CMI and kidney stones (log-likelihood ratio test P = 0.236). Subgroup analyses and interactions indicated that the association between CMI and kidney stone prevalence was notably stronger in individuals who were living with a partner /married and had a poverty income ratio (PIR) of 1.5 to less than 3.5 (P for interaction < 0.05). propensity score matching (PSM) further verified the robustness of our results.

CONCLUSION

Elevated CMI correlates with greater kidney stone prevalence in diabetic individuals, particularly those married or living with a partner and within certain economic statuses. This study supports the hypothesis linking CMI and kidney stones in U.S. diabetic population, suggesting a target demographic for preventive strategies.

Exploring the Critical Role of Tight Junction Proteins in Kidney Disease Pathogenesis

BACKGROUND

Kidney disease poses a significant global health challenge, marked by a rapid decline in renal function due to a variety of causative factors. A crucial element in the pathophysiology of kidney disease is the dysregulation of epithelial cells, which are vital components of renal tissue architecture. The integrity and functionality of these cells are largely dependent on tight junctions (TJ) proteins, complex molecular structures that link adjacent epithelial cells. These TJ not only confer cellular polarity and maintain essential barrier functions but also regulate epithelial permeability.

SUMMARY

TJ proteins are pivotal in their traditional role at cell junctions and in their non-junctional capacities. Recent research has shifted the perception of these proteins from mere structural elements to dynamic mediators of kidney disease, playing significant roles in various renal pathologies. This review explores the multifaceted roles of TJ proteins, focusing on their functions both within and external to the renal epithelial junctions. It highlights how these proteins contribute to mechanisms underlying kidney disease, emphasizing their impact on disease progression and outcomes.

KEY MESSAGES

TJ proteins have emerged as significant players in the field of nephrology, not only for their structural role but also for their regulatory functions in disease pathology. Their dual roles in maintaining epithelial integrity and mediating pathological processes make them promising therapeutic targets for kidney disease. Understanding the intricate contributions of TJ proteins in kidney pathology offers potential for novel therapeutic strategies, aiming to modulate these proteins to halt or reverse the progression of kidney disease.

Evaluation of Genetic Associations with Clinical Phenotypes of Kidney Stone Disease

Background and objective

Previous studies have reported a strong genetic contribution to kidney stone risk. This study aims to identify genetic associations of kidney stone disease within a large-scale electronic health record system.

Methods

We performed genome-wide association studies (GWASs) for nephrolithiasis from genotyped samples of 5571 cases and 83 692 controls. This analysis included a primary GWAS focused on nephrolithiasis and subsequent subgroup GWASs stratified by stone composition types. For significant risk variants, we performed association analyses with stone composition and first-time 24-h urine parameters. To assess disease severity, we investigated the associations with age at first stone diagnosis, age at first stone-related procedure, and time between first and second stone-related procedures.

Key findings and limitations

The primary GWAS analysis identified ten significant loci, all located on chromosome 16 within coding regions of the UMOD gene. The strongest signal was rs28544423 (odds ratio 1.17, 95% confidence interval 1.11-1.23, p = 2.7 × 10-9). In subgroup GWASs stratified by six kidney stone composition subtypes, 19 significant loci were identified including two loci in coding regions (brushite; NXPH1, rs79970906 and rs4725104). The UMOD single nucleotide polymorphism rs28544423 was associated with differences in 24-h excretion of urinary analytes, and the minor allele was positively associated with calcium oxalate dihydrate stone composition (p < 0.05). No associations were found between UMOD variants and disease severity. Limitations include an omitted variable bias and a misclassification bias.

Conclusions and clinical implications

We replicated germline variants associated with kidney stone disease risk at UMOD and reported novel variants associated with stone composition. Genetic variants of UMOD are associated with differences in 24-h urine parameters and stone composition, but not disease severity.

Patient summary

We identify genetic variants linked to kidney stone disease within an electronic health record (EHR) system. These findings suggest a role for the EHR to enable a precision-medicine approach for stone disease.