[Protein Z, polymorphisms in the protein Z gene and thrombosis]

Plasma levels and urinary excretion of protein Z in patients with urolithiasis

OBJECTIVES

Protein Z (PZ) is a γ-carboxyglutamic acid protein present in plasma that is involved in blood coagulation. Detailed analysis of urinary stones from patients with urolithiasis has revealed that PZ is often found in urinary stones composed of calcium oxalate monohydrate. In this study, we compared blood and urinary PZ concentrations between healthy individuals and patients with urolithiasis.

METHODS

Plasma and urine were collected from healthy individuals and patients with urolithiasis who provided informed consent. PZ was detected as a urinary stone matrix protein in some of the patients. PZ was quantified by ELISA, creatinine was measured by the enzymatic method, and the total protein concentration was measured by the Bradford method.

RESULTS

The plasma PZ level was 2.54 ± 1.02 μg/mL in healthy individuals and that in urolithiasis patients classified by stone history were from 1.16 ± 0.77 to 3.73 ± 1.09 μg/mL, which was not significantly different. The urinary excretion of PZ (PZ/creatinine) was also not different in patients with urolithiasis and in healthy individuals (from 54.1 ± 40.9 to 95.4 ± 69.4 ng/mg vs. 73.3 ± 36.0 ng/mg). A positive correlation was found between the plasma PZ level and creatinine-corrected urinary PZ concentration (r = 0.46).

CONCLUSIONS

Both the plasma level and urinary excretion of PZ in urolithiasis patients were not significantly different with normal individuals. PZ detected in urinary stones as a matrix protein is thought to be incorporated into urinary stones regardless of blood and urine levels of PZ.

Protein Z G79A polymorphism and puerperal cerebral venous thrombosis

Protein Z (PZ), a cofactor for PZ-dependent protease inhibitor, is known to play an important role in inhibiting the coagulation cascade. The aim of the study was to investigate whether PZ G79A polymorphism is a risk factor for puerperal cerebral venous thrombosis (CVT). A total of 71 patients with puerperal CVT and 98 healthy controls were genotyped for PZ 79GA polymorphism by polymerase chain reaction-restriction fragment length polymorphism method. In patients, the genotype distribution for GG, GA, and AA genotypes was 22.5%, 43.7%, and 33.8%, and in controls, 25.5%, 40.8%, and 33.7%, respectively. The risk associated with carrying the mutant genotype (GA and AA) versus the wild GG genotype was found to be 1.11 (95% confidence interval: 0.52-2.35; P = .909). There was no significant difference in the clinical features of the patients with and without the polymorphism. We therefore conclude that PZ G79A polymorphism is not a risk factor for puerperal CVT in Indian women.

Protein Z variants associated with protein Z plasma levels and with risk of idiopathic recurrent miscarriage

Protein Z (PZ) deficiency due to anti-PZ autoantibodies and/or mutations in PZgene was linked with adverse pregnancy outcomes, including idiopathic recurrent miscarriage (IRM). We investigated the association of rs3024718, rs3024719, rs3024731, rs3024778, rs3024772, and rs3024735 (G79A) PZ variants and changes in PZ levels in 287 women with IRM, and 308 control women. Of the 6 single nucleotide polymorphisms (SNPs) analyzed, higher minor allele frequency of rs3024735 (G79A) and rs3024731 were seen in IRM cases than in control women. Significantly higher frequencies of rs3024735/G79A G/A and A/A (P< .001), rs3024719 G/A (P= .009), and rs3024731 A/A (P = .012), but not rs3024718 (P= .12), rs3024778 (P = .76), or rs3024772 (P= .27) genotype carriers were seen between IRM cases versus control women, respectively, and was linked with reduced PZ levels. Six-locus (rs3024718/rs3024719/rs3024778/rs3024731/rs3024735/rs3024772) PZhaplotypes analysis demonstrated increased frequency of GAGAAG and AGGTAG and reduced frequency of AGGTGC haplotypes in IRM cases, thereby conferring disease susceptibility and protective nature to these haplotypes, respectively. These results demonstrate that specific PZSNPs and haplotypes are significantly associated with IRM.