Table 4.
Association between the genotype at claudin-14 and calcium excretion in 24-hour urine (n=393) and 2-hour urine collected during sodium chloride infusion (n=370)
| Variables | Homozygotes for the Minor Allele | Heterozygotes | Homozygotes for the Major Allele | P Value |
|---|---|---|---|---|
| rs219739 (C>T) in block A calcium excretion, mg/24 h | 178±85 (n=28) | 191±108a (n=151) | 222±121 (n=214) | <0.01 |
| calcium excretion during NaCl infusion, mg/2 h | 22±14 (n=26) | 28±21 (n=144) | 30±18 (n=200) | 0.03 |
| rs9636632 (A>G), no block calcium excretion, mg/24 h | 174±88 (n=72) | 208±118a (n=191) | 224±120 (n=130) | <0.01 |
| calcium excretion during NaCl infusion, mg/2 h | 26±18 (n=65) | 29±20 (n=185) | 31±19 (n=121) | 0.15 |
| rs2835364 (G>A) in block C calcium excretion, mg/24 h | 87±36 (n=2) | 171±86a (n=63) | 215±118 (n=328) | <0.01 |
| calcium excretion during NaCl infusion, mg/2 h | 14±8 (n=2) | 25±17 (n=61) | 30±20 (n=307) | 0.05 |
| rs7277076 (T>C) in block D calcium excretion, mg/24 h | 164±112a (n=51) | 206±107 (n=198) | 226±123 (n=144) | 0.002 |
| calcium excretion during NaCl infusion, mg/2 h | 27±20 (n=48) | 28±16 (n=189) | 31±23 (n=135) | 0.08 |
| 21:37835184 (D>R), no block calcium excretion, mg/24 h | 159±110b (n=54) | 208±104 (n=200) | 224±127 (n=139) | 0.002 |
| calcium excretion during NaCl infusion, mg/2 h | 23±19a (n=53) | 29±17 (n=189) | 31±23 (n=128) | 0.02 |
| rs219778 (A>G) in block E calcium excretion, mg/24 h | 142±84a (n=23) | 198±106 (n=127) | 218±120 (n=243) | 0.004 |
| calcium excretion during NaCl infusion, mg/2 h | 28±19 (n=23) | 26±15 (n=115) | 30±21 (n=232) | 0.10 |
| rs219780 (C>T) in block E calcium excretion, mg/24 h | 150±77 (n=9) | 193±111 (n=107) | 214±117 (n=277) | 0.04 |
| calcium excretion during NaCl infusion, mg/2 h | 40±24.2 (n=9) | 26±15 (n=99) | 30±20 (n=262) | 0.04 |
Findings about rs219755 located in the block B are reported in Table 3. Calcium excretion in 24-hour urine and 2-hour urine collected at the end of the NaCl infusion test (intravenous infusion of 2 L of 0.9% NaCl in 120 minutes) was tested in patients with different genotypes at the single-nucleotide polymorphisms with the most significant association with calcium excretion among those of each 3′ region haplotype block of claudin-14. D is an unknown base of 21:37835184 single-nucleotide polymorphism, which is not yet codified within international databases. P value for genotype-phenotype association was estimated with linear regression. Comparison between groups was performed with one-way ANOVA and Tukey test. NaCl, sodium chloride.
P<0.05 versus homozygotes for the major allele.
P<0.05 versus heterozygotes and P<0.01 versus homozygotes for the major allele.