Genetic Risk Factors for Idiopathic Urolithiasis: A Systematic Review of the Literature and Causal Network Analysis

Association of single nucleotide genetic polymorphisms of vitamin D receptor and calcium-sensitive receptor with calcium-containing kidney stones in Chinese Dai populations: a prospective multi-center study

PURPOSE

To evaluate the association between vitamin D receptor (VDRs) and calcium-sensitive receptor (CaSR) gene polymorphisms and calcium-containing kidney stones (CCKS) in Dai populations.

METHODS

A total of 160 CCKS patients and 87 healthy controls were included in this study. CCKS was confirmed using urological computed tomography (CT), plain abdominal radiograph, or surgical lithotomy. Stone samples obtained during surgery were analyzed using infrared spectroscopy. Venous blood and 24-h urine samples were collected and analyzed using Sanger sequencing and high-performance liquid chromatography, respectively. Genetic variants in the VDR gene (rs7975232, rs2228570, rs731236, and rs1544410) and CaSR gene (rs7652589, rs1801725, and rs1042636) were identified through sequence analysis.

RESULTS

Analysis of genotype and allele frequencies revealed that the rs7975232 polymorphism in the VDR gene and the rs7652589 allele in the CaSR gene were significantly associated with CCKS. Furthermore, patients carrying the AC and AA genotypes of rs7975232 showed a higher incidence of hypocitraturia compared to those with other genotypes (p < 0.05). The AA and GG genotypes of rs1042636 and the AA genotype of rs7652589 were significantly associated with hypercalciuria (p < 0.05).

CONCLUSION

CCKS in this study population may be closely related to hypocitraturia caused by the VDR locus rs7975232 polymorphism and hypercalciuria caused by the CaSR locus rs1042636 and rs7652589 polymorphism.

Intravenous iron-induced hypophosphatemia and kidney stone disease

Patients with Crohn's disease are at increased risk for symptomatic nephrolithiasis. Stones in these patients are most commonly composed of calcium oxalate monohydrate or mixed calcium-oxalate and calcium-phosphate. Precipitation of both minerals depends on urinary pH, calcium, phosphate and oxalate excretion. The present manuscript reports on two patients with Crohn's disease and bowel resection, in whom the onset of symptomatic urolithiasis occurred after repeated infusions of ferric carboxymaltose - a drug, which is known to cause hyperphosphaturia. The present study shows that ferric carboxymaltose-induced hyperphosphaturia can be associated with kidney stone formation and symptomatic urolithiasis, especially in patients treated with calcitriol. Calcitriol has been shown to mitigate ferric carboxymaltose-induced secondary hyperparathyroidism and hyperphosphaturia, but is known to increase urinary calcium excretion. Chemical analysis of recovered stones revealed that they were mixed calcium oxalate and phosphate stones. Ring-like deposition of iron detected by spatially resolved elemental analysis using laser ablation-inductively coupled plasma mass spectrometry, showed that the stones also contained iron. Based on our findings, we propose that patients with inflammatory bowel disease requiring intravenous iron therapy should be carefully monitored for the development of hypophosphatemia and urolithiasis. If hypophosphatemia occurs in such patients, calcitriol should be used with caution.

Polymorphic variations and mRNA expression of the genes encoding interleukins as well as enzymes of oxidative and nitrative stresses as a potential risk of nephrolithiasis development

Urolithiasis is one of the most common urological diseases worldwide with an unclear aetiology. However, a growing body of evidence suggests the potential role of molecular disturbances of the inflammation as well as oxidative and nitrative stresses, in the pathogenesis of urolithiasis. Therefore, we aimed to detect the potential association between six selected single-nucleotide polymorphisms (SNPs) and the development of nephrolithiasis. Moreover, we verified the association of urolithiasis development and mRNA expression of IL-6, IL-8, SOD2, and NOS2 in peripheral blood mononuclear cells (PBMCs). Total genomic DNA and mRNA were isolated from the peripheral blood of 112 patients with urolithiasis and 114 healthy subjects. Using Taq-Man® probes, we genotyped the following SNPs: rs1800797 and rs2069845 in IL-6, rs2227307 in IL-8, rs4880 in SOD2, rs2297518 and rs2779249 in NOS2. In turn, the evaluation of mRNA expression was performed using real-time PCR and 2-ΔCt methods. We found that the C/T genotype of the c.47 T>C-SOD2 SNP increased the frequency of urolithiasis occurrence whereas the T/T homozygote of the same polymorphism decreased the risk of urolithiasis development in the Polish population. Moreover, our study confirmed that patients with urolithiasis were characterised by decreased IL-6, IL-8, and SOD2 mRNA expression levels compared to the controls. In conclusion, our results suggest that polymorphic variants and changes in mRNA expression of IL-6, IL8, SOD2, and NOS2 may be involved in the pathophysiology of urolithiasis.

Past, present and future of genomics for kidney stone disease

PURPOSE OF REVIEW

To summarize the latest findings and developments in genomics for kidney stone disease (KSD) that help to understand hereditary pathomechanisms, identify high risk stone formers, provide early treatment and prevent recurrent kidney stone formation.

RECENT FINDINGS

Several gene loci associated to KSD have presently been discovered in large Genome-wide association studies. Monogenic causes are rare, but are thought to have higher penetrance, while polygenic causes are more frequent with less penetrance. Although there is a great effort identifying genetic causes of KSD, targeted therapies are scarce.

SUMMARY

There have been great advancements in genetic research in identifying genetic variants associated with KSD. Identifying these variants and understanding the underlying pathophysiology will not only provide individual risk assessment but open the way for new treatment targets and preventive care strategies.

The effect of ALPL gene polymorphism on the development of urolithiasis in the Turkish population

Urinary system stones have a complex pathophysiology affected by environmental and genetic factors. To confirm whether ALPL gene polymorphisms are an effective universal risk factor for the development of urolithiasis, we aimed to investigate ALPL gene polymorphism in Turkish population. Our study was carried out with 187 patients with urolithiasis and 92 healthy volunteers (control group) who were not diagnosed with urolithiasis either in themselves or in their families, applied to Emergency Medicine Clinic of Health Sciences University Haydarpasa Numune Training and Research Hospital in Istanbul, Turkey between November 2021 and February 2022, prospectively. In order to evaluate the relationship between ALP gene (rs1256328) polymorphism and urolithiasis, blood samples were analyzed by quantitative Real Time PCR (qPCR) method.  Male gender (OR:3.785; 95% CI:2.118-6.763; p<0.001), increased BUN level (OR:1.082; 95% CI:1.013-1.156; p=0.019), increased NLR level (OR:1.149; 95 %CI:1.033-1.277; p=0.011) and heterozygous genotype (OR:2.353; 95% CI:1.31-4.225; p=0.004) were determined as independent risk factors for the development of urolithiasis. The presence of heterozygous (CT) genotype in the ALPL rs1256328 gene region in the Turkish population is associated with an increased risk of urolithiasis. This suggests that ALPL rs1256328 gene polymorphism can be used as a genetic marker in the Turkish population.

Metabolic and Genetic Evaluation in Children with Nephrolithiasis

OBJECTIVE

To evaluate metabolic and genetic abnormalities in children with nephrolithiasis attending a referral center in North India.

METHODS

The patients aged 1-18 y old with nephrolithiasis underwent biochemical evaluation and whole-exome sequencing. The authors evaluated for monogenic variants in 56 genes and compared allele frequency of 39 reported polymorphisms between patients and 1739 controls from the GenomeAsia 100 K database.

RESULTS

Fifty-four patients, aged 9.1 ± 3.7 y were included. Stones were bilateral in 42.6%, familial in 33.3%, and recurrent in 25.9%. The most common metabolic abnormalities were hypercalciuria (35.2%), hyperoxaluria (24.1%), or both (11.1%), while xanthinuria (n = 3), cystinuria (n = 1), and hyperuricosuria (n = 1) were rare. Exome sequencing identified an etiology in 6 (11.1%) patients with pathogenic/likely pathogenic causative variants. Three variants in MOCOS and one in ATP7B were pathogenic; likely pathogenic variants included MOCOS (n = 2), AGXT, and SLC7A9 (n = 1, each). Causality was not attributed to two SLC34A1 likely pathogenic variants, due to lack of matching phenotype and dominant family history. Compared to controls, allele frequency of the polymorphism TRPV5 rs4252402 was significantly higher in familial stone disease (allele frequency 0.47 versus 0.53; OR 3.2, p = 0.0001).

CONCLUSION

The chief metabolic abnormalities were hypercalciuria and hyperoxaluria. A monogenic etiology was identified in 11% with pathogenic or likely pathogenic variants using a gene panel for nephrolithiasis. Heterozygous missense variants in the sodium-phosphate cotransporter SLC34A1 were common and required evaluation for attributing pathogenicity. Rare polymorphisms in TRPV5 might increase the risk of familial stones. These findings suggest that a combination of metabolic and genetic evaluation is useful for determining the etiology of nephrolithiasis.

Scoping review of recent evidence on the management of pediatric urolithiasis: summary of meta-analyses, systematic reviews and relevant randomized controlled trials

This scoping review aimed to evaluate and summarize the recent 10 year pediatric urolithiasis literature with a particular focus on systematic reviews, randomized-controlled trials (RCT) and meta-analysis. The systematic literature search performed on September 1, 2021, restricted to the recent 10 years, focused on pediatric urolithiasis that are RCTs, meta-analysis and systematic reviews. The summarized literature included etiology, diagnostics, medical and surgical management. GRADE criteria are used to evaluate and standardize the reporting of evidence quality. A total of 33 relevant articles were included. The recent high-level studies included topics of genetic and diet association with pediatric stone formation, diagnostic assessment, medical management intervention including medical dissolution and expulsion therapy. The study extended to include the efficacy and safety of extracorporeal lithotripsy, percutaneous nephrolithotomy and retrograde intrarenal surgery. However, evidence quality was ranked "very-low" or "low". Based on the GRADE criteria downgrading of the quality level was due to heterogeneity and low precision. A majority of the RCTs were categorized as having a "high" to "uncertain" risk of bias. The relevant RCTs, meta-analyses and systematic reviews within the past decade are of low quality. Consequently, the research provided no clear evidence-based recommendations for managing pediatric urolithiasis. More rigorous research and high-quality studies are needed to determine the best practices.

Skeletal and extraskeletal disorders of biomineralization

The physiological process of biomineralization is complex and deviation from it leads to a variety of diseases. Progress in the past 10 years has enhanced understanding of the genetic, molecular and cellular pathophysiology underlying these disorders; sometimes, this knowledge has both facilitated restoration of health and clarified the very nature of biomineralization as it occurs in humans. In this Review, we consider the principal regulators of mineralization and crystallization, and how dysregulation of these processes can lead to human disease. The knowledge acquired to date and gaps still to be filled are highlighted. The disorders of mineralization discussed comprise a broad spectrum of conditions that encompass bone disorders associated with alterations of mineral quantity and quality, as well as disorders of extraskeletal mineralization (hyperphosphataemic familial tumoural calcinosis). Included are disorders of alkaline phosphatase (hypophosphatasia) and phosphate homeostasis (X-linked hypophosphataemic rickets, fluorosis, rickets and osteomalacia). Furthermore, crystallopathies are covered as well as arterial and renal calcification. This Review discusses the current knowledge of biomineralization derived from basic and clinical research and points to future studies that will lead to new therapeutic approaches for biomineralization disorders.

Interior definition of the calyceal orientation suitable for percutaneous nephrolithotripsy via mobile software

To date, there is no paper on defining the puncture of a kidney from the interior view of the pelvicalyceal system (PCS) to alleviate its performance. The objective of this study is to define the usefulness of the Rubik's Cube method determining calyceal orientation from inside via mobile software for the percutaneous nephrolithotripsy (PCNL). Over September 2019-September 2020, 25 patients with indications for PCNL were enrolled in this single-arm study. All patients underwent computed tomography (CT)-urography. Primary endpoints were the duration of renal cavity puncture, number of attempts and success rate. Complication rate ordered according to Clavien-Dindo classification was analyzed as a secondary endpoint. The stone-free rate was 91%. The same experienced urologist performed all procedures through the single-access PCNL without puncture site reposition. The puncture was made through the upper, middle, and lower calyx in 9, 12 and 4 cases, respectively. The mean duration of cavity puncture was 2.8 ± 1.1 min. The mean number of attempts to reach desirable calyx was 1.4 ± 0.6. It should be noted that there were no cases with three and more punctures. The overall complication rate was 28% (7/25) when only one patient experienced ≥ 3 Grade. The proposed Rubik's Cube method facilitates preoperative planning of PCNL and makes that procedure easier for specialists and safer for the patients.

Aggregation of Nanochemical Microcrystals in Urine Promotes the Formation of Urinary Calculi

With the increasing incidence and recurrence rate of urinary calculi, urinary calculi have become a serious health risk, and the research on urinary calculi has become the focus of public attention. At present, the research results on the formation mechanism of urinary calculi are not ideal, and there is no unified conclusion. In order to further study the influencing factors of the formation of urinary calculi and provide new ideas for the prevention and clinical treatment of urinary calculi, the influence of agglomeration of nanochemical microcrystals in urine on urinary calculi was studied in this paper. In this study, fresh morning urine was collected from 10 urological stone patients and 10 healthy controls without urological stone in the urology department of a hospital. After processing the experimental specimens, we first use flame atomic absorption spectrometry and alcian blue colorimetric method to detect the content of Ca2+ and citrate in the urine and then use the nanoparticle size analyzer to detect the microcrystals in the urine. Diameter, distribution, degree of aggregation and potential, and finally HRTEM observation to observe the morphology, chemical composition, and element composition of the nanocrystals. The results showed that the content of Ca2+ and lemon hydrochloric acid in the urine of the experimental group was lower than that of the control group. The particle size of the nanocrystals increased with the increase in the pore size of the membrane. The average particle size of the experimental group increased gradually from 163 ± 31 nm to 3219 ± 863 nm, while the average particle size of the control group increased from 183 ± 65 nm to 997 ± 522 nm. The mean value of the potential decreased with the increase in the pore size of the filter membrane. The change amplitude of the experimental group was 6.57 mV, while the change amplitude of the control group was only 1.75 mV. In the composition of nanocrystals, element O accounts for the most, accounting for 42.54% of all elements. This indicates that the aggregation of nanocrystals in urine will lead to the rapid increase in the size of nanocrystals, which will eventually lead to the formation of stones.

Klotho (rs1207568 and rs564481) gene variants and colorectal cancer risk

BACKGROUND/AIMS

Whereas colorectal cancer (CRC) is the third most common cancer worldwide, klotho gene has been reported as a tumor suppressor gene. Therefore, the aim of this study was to investigate the association between klotho (rs1207568 and rs564481) variants and CRC in Egyptian patients.

MATERIALS AND METHODS

A case-control study comprising 100 patients with CRC and 100 age- and sex-matched healthy controls was conducted. Genotyping of klotho was performed by polymerase chain reaction with confronting two-pair primers.

RESULTS

The frequencies of the A allele of rs1207568 and the AC haplotype were significantly higher in patients with CRC than in the controls (p=0.019 and p=0.005, respectively).

CONCLUSION

We propose that klotho (rs1207568 and rs564481) variants play a significant role in colorectal carcinogenesis and that the klotho protein could be a target for oncotherapy.

Fatty acid-binding protein 4 downregulation drives calcification in the development of kidney stone disease

Nephrolithiasis is a significant source of morbidity, and its incidence has increased significantly over the last decades. This rise has been attributed to concurrent increasing rates of obesity, associated with a 3-time risk of developing NL. To date, the mechanism by which obesity is linked to stone formation has not been elucidated. We aimed to utilize a transcriptomics approach to discover the missing link between these two epidemic diseases. We investigated gene expression profiling of nephrolithiasis patients by two RNA-sequencing approaches: comparison between renal papilla tissue with and without the presence of calcified Randall's plaques (RP), and comparison between the papilla, medulla, and cortex regions from within a single recurrent stone forming kidney. Results were overlaid between differently expressed genes found in the patient cohort and in the severely lithogenic kidney to identify common genes. Overlay of these two RNA-sequencing datasets demonstrated there is impairment of lipid metabolism in renal papilla tissue containing RP linked to downregulation of fatty acid binding protein (FABP) 4. Immunohistochemistry of human kidney specimens and microarray analysis of renal tissue from a nephrolithiasis mouse model confirmed that FABP4 downregulation is associated with renal stone formation. In a FABP4 knockout mouse model, FABP4 deficiency resulted in development of both renal and urinary crystals. Our study revealed that FABP4 plays an important, previously unrecognized role in kidney stone formation, providing a feasible mechanism to explain the link between nephrolithiasis and metabolic syndrome.

Genetic factors of polygenic urolithiasis

The article summarizes the findings of Russian and international studies of the genetic aspects of polygenic urolithiasis associated with impairment of calcium metabolism. The article analyzes the genetic risk factors of polygenic nephrolithiasis that show significant association with the disease in case-control studies and Genome-Wide Association Studies (16 genes). We described the gene functions involved in concrement formation in polygenic nephrolithiasis. The modern molecular and genetic technologies (DNA microarray, high-throughput DNA sequencing, etc.) enable identification of the genetic predisposition to a specific disease, realization of the individualized treatment of the patient, and carrying out timely preventive measures among the proband's relatives.

Meeting report of the "Symposium on kidney stones and mineral metabolism: calcium kidney stones in 2017"

A symposium on kidney stones and mineral metabolism held on December 2017 in Brussels, Belgium was the first international multidisciplinary conference of the International Collaborative Network on Kidney Stones and Mineral Metabolism. This meeting addressed epidemiology, underlying pathophysiological mechanisms, genetics, pathological, as well as clinical and research topics. The participants included clinicians and recognized experts in the field from Europe and the United States interacted closely during the symposium which promoted a chance to explore new frontiers in the field of kidney stone disease. This manuscript summarizes some of the major highlights of the meeting.

Hereditary hypophosphatemic rickets with hypercalciuria: pathophysiology, clinical presentation, diagnosis and therapy

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH; OMIM: 241530) is a rare autosomal recessive disorder with an estimated prevalence of 1:250,000 that was originally described by Tieder et al. Individuals with HHRH carry compound-heterozygous or homozygous (comp/hom) loss-of-function mutations in the sodium-phosphate co-transporter NPT2c. These mutations result in the development of urinary phosphate (Pi) wasting and hypophosphatemic rickets, bowing, and short stature, as well as appropriately elevated 1,25(OH)₂D levels, which sets this fibroblast growth factor 23 (FGF23)-independent disorder apart from the more common X-linked hypophosphatemia. The elevated 1,25(OH)₂D levels in turn result in hypercalciuria due to enhanced intestinal calcium absorption and reduced parathyroid hormone (PTH)-dependent calcium-reabsorption in the distal renal tubules, leading to the development of kidney stones and/or nephrocalcinosis in approximately half of the individuals with HHRH. Even heterozygous NPT2c mutations are frequently associated with isolated hypercalciuria (IH), which increases the risk of kidney stones or nephrocalcinosis threefold in affected individuals compared with the general population. Bone disease is generally absent in individuals with IH, in contrast to those with HHRH. Treatment of HHRH and IH consists of monotherapy with oral Pi supplements, while active vitamin D analogs are contraindicated, mainly because the endogenous 1,25(OH)₂D levels are already elevated but also to prevent further worsening of the hypercalciuria. Long-term studies to determine whether oral Pi supplementation alone is sufficient to prevent renal calcifications and bone loss, however, are lacking. It is also unknown how therapy should be monitored, whether secondary hyperparathyroidism can develop, and whether Pi requirements decrease with age, as observed in some FGF23-dependent hypophosphatemic disorders, or whether this can lead to osteoporosis.

Familial risks in and between stone diseases: sialolithiasis, urolithiasis and cholelithiasis in the population of Sweden

BACKGROUND

According to the literature the three stone diseases, sialolithiasis (SL), urolithiasis (UL) and cholelithiasis (CL) share comorbidities. We assess familial and spouse risks between these stone disease and compare them to familial risks for concordant (same) stone disease.

METHODS

Study population including familiar relationships was obtained from the Swedish Multigeneration Register and stone disease patients were identified from nation-wide medical records. Standardized incidence ratios (SIRs) were calculated for 0-83 year old offspring when their first-degree relatives were diagnosed with stone disease and the rates were compared to individuals without a family history of stone disease. Numbers of offspring with SL were 7906, for UL they were 170,757 and for CL they were 204,369.

RESULTS

SIRs for concordant familial risks were 2.06 for SL, 1.94 for UL and 1.82 for CL. SIRs for SL and UL were slightly higher for women than for men. Familial risks between stone diseases were modest. The highest risk of 1.17 was for UL when family members were diagnosed with CL, or vice versa. The SIR for UL was 1.15 when family members were diagnosed with SL. Familial risks among spouses were increased only for UL-CL pairs (1.10).

CONCLUSIONS

Familial risks for concordant SL were 2.06 and marginally lower for the other diseases. Familial risks between stone diseases were low but higher than risks between spouses. The data show that familial clustering is unique to each individual stone disease which would imply distinct disease mechanisms. The results cast doubt on the reported comorbidities between these diseases.

Polymorphisms of PTH (Parathyroid Hormone) Gene and Risk of Kidney Stone Disease: A Case-Control Study from West Bengal, India

OBJECTIVE

To investigate the potential contribution of parathyroid hormone (PTH) gene polymorphisms in kidney stone disease (KSD), a global clinical problem impacting major burden on public health care system worldwide.

METHODS

A case-control study was performed in West Bengal (India) with 152 patients reported with calcium-rich stone in kidney and 144 corresponding normal healthy individuals as controls. To identify genetic variants of PTH, the entire coding region, exon-intron boundaries and a few hundred nucleotides downstream the exon 3 (3' UTR region) was bi-directionally sequenced for all the study participants.

RESULTS

Two intronic (rs694 and rs6254) and one synonymous (rs6256, located in exon 3) variant were identified along with 2 single nucleotide polymorphisms (SNPs) (rs307247 and rs307248) in the 3' UTR of the PTH gene. Allele and genotype frequency analysis of these SNPs revealed that rs6254 and rs6256 had moderate association with increased risk of KSD. The 2 SNPs (rs307247 and rs307248) of the 3' UTR, which were in strong linkage disequilibrium, were found to be significantly associated with kidney stone risk in the population of West Bengal, India.

CONCLUSION

This is the first time report in the world, regarding association of PTH gene polymorphisms with KSD. Our finding suggests that PTH gene polymorphisms can be used as potential genetic markers for early detection of KSD and for preventing its occurrence. Additional studies with larger sample size are essential to validate our result.

Familial risks in urolithiasis in the population of Sweden

OBJECTIVE

To assess detailed familial risks for medically diagnosed urolithiasis (UL, urinary tract stone disease) based on nationwide hospital and population records.

PATIENTS/SUBJECTS AND METHODS

Subjects were identified from the Swedish Multigeneration Register in which there were 211 718 patients with UL. Standardised incidence ratios (SIRs) were calculated by comparison to individuals without a family history of UL.

RESULTS

The highest familial SIRs were invariably found for the same (concordant) type of UL: 2.18 for kidney, 2.20 for ureter, and 1.93 for bladder. SIRs increased from 1.84, when one parent was affected, to 3.54 when both parents were affected, which was a multiplicative interaction. The SIR was 1.79 when one sibling was affected but it increased to 24.91 when two siblings were affected. Such excessive risks (5.2% of familial cases) are probably explained by high-penetrant genes. A low SIR of 1.29 between spouses suggested a minor contribution by shared environmental factors on the familial risk.

CONCLUSIONS

The results point to underlying genetic causes for the observed familial clustering and establish the genetic landscape of UL. Family histories should be taken in UL diagnostics and prevention could follow guidelines recommended for recurrent UL.