Nephrolithiasis is a multifactorial disease caused by environmental, hormonal, and genetic factors. Genetic polymorphisms of
Urolithiasis is a global problem affecting almost all populations in the world. In developed countries, the prevalence rate of urolithiasis was reported to be 4%~20%. In Taiwan, the prevalence was reported to be 9.6% [
Urolithiasis often involves the formation of stones containing calcium compounds, mainly calcium oxalate and calcium phosphate, which account for 70%~80% of reported cases of urolithiasis. Calcium urolithiasis is thought to have a physicochemical origin, involving processes such as nucleation, growth, aggregation, and retention of crystals in the urine. The crystals include inorganic (e.g., calcium, uric acid, phosphate, and citrate) and organic substances (the Tamm-Horsfall glycoprotein and osteopontin) [
Our previous study indicated that genetic polymorphisms of
We enrolled 365 patients who fulfilled the diagnostic criteria for nephrolithiasis at Kaohsiung Medical University Hospital (KMUH). Radiographic and echographic documentation of urinary stones in these patients were collected. Stone samples were obtained either from spontaneous passage or by surgical manipulation. We also collected clinical information such as age, gender, family history of nephrolithiasis, and episodes of stone recurrence. The past history of the stone episode was traced back to the whole life as far as patients could remember. Patients with at least 2 symptomatic episodes (at least 6 months apart) or new stones after treatment were classified into the recurrent group, and those with only 1 episode were classified into the single group. All subjects provided informed consent. The study protocol conformed to the
DNA was extracted from blood samples collected from subjects. Blood cells were first treated with 0.5% sodium dodecyl sulfate lysis buffer and then with protease K (1 mg/mL) for 4 h at 60°C to digest the nuclear proteins. Total DNA was harvested using a Gentra (QIAGEN Inc., Valencia, CA) extraction kit and 70% alcohol precipitation, as in our previous study [
We selected seven tagging SNPs (rs11673492, rs7257602, rs7251246, rs890934, rs10420685, rs2607420, and rs2290692) with a minor allele frequency greater than 10% in the Han Chinese Beijing population from the HapMap database (
Graphical overview of the genotyped human
Intracellular Ca2+ ([Ca2+]
SAS 9.1 for Windows (Cary, NC) was used for all statistical analyses. Statistical differences in genotypes and allelic frequencies between cases and controls were assessed by
We included 365 nephrolithiasis patients in this study. Table
Basal characteristics of patients with nephrolithiasis and of normal controls.
Characteristic | Patients with nephrolithiasis |
---|---|
Number of subjects | 365 |
Gender: male, number (%) | 250 (68.5%) |
Age (years)a |
|
Range | 24~86 |
Among cases, 113 patients had had recurrent episodes, and 116 patients had had a single episode. We tested whether the rs11673492, rs28493229, rs7257602, rs7251246, rs890934, rs10420685, rs2607420, and rs2290692 genotypes were associated with the stone number or recurrence of calcium nephrolithiasis. As shown in Table
Association analysis of ITPKC single-nucleotide polymorphisms (SNPs) and clinical medical records data of patients with kidney stones.
SNP | Genotype | Stone numbers (%) |
|
Stone frequency (%) |
|
||
---|---|---|---|---|---|---|---|
Multiple | Single | Recurrence | Nonrecurrence | ||||
rs11673492 | TT | 12 (9.7) | 10 (8.1) | 0.9050 | 11 (9.7) | 10 (8.7) | 0.4025 |
CT | 58 (46.8) | 59 (47.6) | 46 (40.7) | 57 (49.6) | |||
CC | 54 (43.5) | 55 (44.3) | 56 (49.6) | 48 (41.7) | |||
|
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rs28493229 | CG | 18 (14.8) | 10 (8.1) | 0.1032 | 16 (14.4) | 9 (7.9) | 0.1198 |
GG | 104 (85.2) | 113 (91.9) | 95 (85.6) | 105 (92.1) | |||
|
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rs7257602 | GG | 32 (25.8) | 24 (19.2) | 0.3705 | 27 (23.9) | 23 (19.8) | 0.7665 |
AG | 55 (44.4) | 65 (52.0) | 54 (47.8) | 58 (50.0) | |||
AA | 37 (29.8) | 36 (28.8) | 32 (28.3) | 35 (30.2) | |||
|
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rs7251246 | GG | 38 (30.7) | 30 (24.0) | 0.2634 | 29 (25.7) | 33 (28.5) | 0.7521 |
GA | 50 (40.3) | 63 (50.4) | 52 (46.0) | 55 (47.4) | |||
AA | 36 (29.0) | 32 (25.6) | 32 (28.3) | 28 (24.1) | |||
|
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rs890934 | TT | 23 (18.5) | 29 (23.2) | 0.3919 | 23 (20.3) | 24 (20.7) | 0.9975 |
GT | 58 (46.8) | 62 (49.6) | 55 (48.7) | 56 (48.3) | |||
GG | 43 (34.7) | 34 (27.2) | 35 (31.0) | 36 (31.0) | |||
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rs10420685 | GG | 7 (5.6) | 5 (4.0) | 0.7842 | 6 (5.3) | 6 (5.2) | 0.8333 |
AG | 43 (34.7) | 41 (33.1) | 37 (32.7) | 42 (36.5) | |||
AA | 74 (59.7) | 78 (62.9) | 70 (62.0) | 67 (58.3) | |||
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rs2607420 | CC | 10 (8.1) | 9 (7.2) | 0.9618 | 10 (8.9) | 9 (7.8) | 0.9191 |
CT | 51 (41.5) | 52 (41.6) | 43 (38.4) | 47 (40.5) | |||
TT | 62 (50.4) | 64 (51.2) | 59 (52.7) | 60 (51.7) | |||
|
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rs2290692 | GG | 38 (30.7) | 28 (22.4) | 0.2161 | 28 (24.8) | 32 (27.6) | 0.8602 |
CG | 50 (40.3) | 63 (50.4) | 53 (46.9) | 54 (46.5) | |||
CC | 36 (29.0) | 34 (27.2) | 32 (28.3) | 30 (25.9) |
Previous studies indicated that renal stones may cause renal impairment and decrease renal function [
Association analysis of ITPKC single-nucleotide polymorphisms (SNPs) and clinical biochemical data of patients with kidney stones.
SNP | Genotype | Sample number (%) | MDRD |
|
C-G |
|
---|---|---|---|---|---|---|
(mL/min/1.73 m2) | (mL/min) | |||||
rs11673492 | TT | 32 (8.8) |
|
0.1471 |
|
0.2342 |
CT | 164 (45.1) |
|
|
|||
CC | 168 (46.1) |
|
|
|||
|
||||||
rs28493229 | CC | 0 (0.0) | — | 0.5622 | — | 0.8885 |
CG | 42 (12.5) |
|
|
|||
GG | 295 (87.5) |
|
|
|||
|
||||||
rs7257602 | GG | 92 (25.3) |
|
0.2855 |
|
0.4558 |
AG | 164 (45.0) |
|
|
|||
AA | 108 (29.7) |
|
|
|||
|
||||||
rs7251246 | GG | 96 (26.4) |
|
0.0990 |
|
|
GA | 164 (45.0) |
|
|
|||
AA | 104 (28.6) |
|
|
|||
|
||||||
rs890934 | TT | 77 (21.1) |
|
0.4380 |
|
0.1932 |
GT | 180 (49.3) |
|
|
|||
GG | 108 (29.6) |
|
|
|||
|
||||||
rs10420685 | GG | 16 (4.4) |
|
0.2153 |
|
0.1545 |
AG | 126 (34.6) |
|
|
|||
AA | 222 (61.0) |
|
|
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rs2607420 | CC | 27 (7.4) |
|
|
|
|
CT | 143 (39.3) |
|
|
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TT | 194 (53.3) |
|
|
|||
|
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rs2290692 | GG | 93 (19.4) |
|
0.4016 |
|
0.0784 |
CG | 164 (34.2) |
|
|
|||
CC | 107 (46.4) |
|
|
The mechanism by which ITPKC influences cellular signaling is not clear. Thus, we transfected ITPKC plasmids into cells and evaluated the intracellular calcium mobilization. As shown in Figure
Effects of ITPKC on calcium influx in HEK293 cells. Thapsigargin (TG; 2
Nephrolithiasis is caused by a variety of conditions, including metabolic disorders and anatomical defects. It is considered a metabolic disorder commonly associated with type 2 diabetes, obesity, dyslipidemia, and hypertension. Most cases of nephrolithiasis are idiopathic; in such cases, there is undoubtedly a genetic predisposition, but both environmental and lifestyle factors may play important roles [
Calcium nephrolithiasis is a type of calcium metabolic disorder, and most renal stones contain calcium. Formation of stones may also result from injury and inflammation of the renal tubular epithelium. Recent study indicated that crystals deposition or formation inside the kidney not only directly causes renal epithelial cell damage but also may induce immune response [
In this study, we found no significant associations between genotypes of
In conclusion, we found that rs2607420 in the intron region of the ITPKC gene is associate with estimated creatinine clearance in patients with calcium nephrolithiasis.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Wei-Chih Kan and Yii-Her Chou contributed equally to the paper.
This work was supported by grants from Chi-Mei Medical Center, Kaohsiung Medical University Research Foundation (101CM-KMU-08), and Taipei Medical University (TMU101-AE1-B14).