Factor V Leiden and Prothrombin Gene Mutation: Risk Factors for Osteonecrosis of the Femoral Head in Adults

T-786C polymorphism of the endothelial nitric oxide synthase gene and neuralgia-inducing cavitational osteonecrosis of the jaws

OBJECTIVE

We hypothesized that, similar to idiopathic hip osteonecrosis, the T-786C mutation of the endothelial nitric oxide synthase (eNOS) gene affecting nitric oxide (NO) production was associated with neuralgia-inducing cavitational osteonecrosis of the jaws (NICO).

DESIGN

In 22 NICO patients, not having taken bisphosphonates, mutations affecting NO production (eNOS T-786C, stromelysin 5A6A) were measured by polymerase chain reaction. Two healthy normal control subjects were matched per case by race and gender.

RESULTS

Homozygosity for the mutant eNOS allele (TT) was present in 6 out of 22 patients (27%) with NICO compared with 0 out of 44 (0%) race and gender-matched control subjects; heterozygosity (TC) was present in 8 patients (36%) versus 15 control subjects (34%); and the wild-type normal genotype (CC) was present in 9 patients (36%) versus 29 controls (66%) (P = .0008). The mutant eNOS T-786C allele was more common in cases (20 out of 44 [45%]) than in control subjects (15 out of 88 [17%]) (P = .0005). The distribution of the stromelysin 5A6A genotype in cases did not differ from control subjects (P = .13).

CONCLUSIONS

The eNOS T-786C polymorphism affecting NO production is associated with NICO, may contribute to the pathogenesis of NICO, and may open therapeutic medical approaches to treatment of NICO through provision of L-arginine, the amino-acid precursor of NO.

Osteonecrosis of the metacarpal head in a patient with a prothrombin 20210A gene mutation

Osteonecrosis of the metacarpal head is rare and of unknown cause. We describe a 17-year-old girl with osteonecrosis of the fourth metacarpal head and a mutated prothrombin 20210A gene, which suggests a possible relation between a hypercoagulable state and osteonecrosis of the metacarpal head.

Thrombophilia, hypofibrinolysis, the eNOS T-786C polymorphism, and multifocal osteonecrosis

BACKGROUND

We examined the hypothesis that thrombophilia, hypofibrinolysis, and the endothelial nitric oxide synthase (eNOS) T-786C polymorphism are common, potentially treatable, and similar pathophysiologic causes of multifocal (three sites or more) and unifocal (single-site) osteonecrosis.

METHODS

We prospectively evaluated twenty-six consecutively referred adults with multifocal osteonecrosis, who included thirteen with idiopathic multifocal osteonecrosis and thirteen with secondary multifocal osteonecrosis (resulting from steroid therapy in ten and alcoholism in three). We compared these patients with race, sex, and age-matched normal control subjects and with patients with idiopathic unifocal and secondary unifocal osteonecrosis, respectively. Using polymerase chain reaction and serologic measures, we studied thrombophilic and hypofibrinolytic mutations and the eNOS T-786C polymorphism.

RESULTS

The total number of polymerase chain reaction and serologic thrombophilic-hypofibrinolytic abnormalities and the eNOS T-786C polymorphism did not differ between patients with idiopathic (p > 0.5) or secondary (p > 0.5) multifocal and unifocal osteonecrosis. The frequency of low free protein-S levels (<66%) in patients with secondary multifocal osteonecrosis (four of eleven patients) was higher than that in the control subjects (one of fifty-nine) (risk ratio = 21.5; 95% confidence interval, 2.6 to 174; p = 0.0016, Benjamini-Hochberg adjusted p [Bp] = 0.004). Factor-V Leiden heterozygosity was present in two of thirteen patients with secondary multifocal osteonecrosis compared with none of sixty-four control subjects (p = 0.027, Bp = 0.008). For eleven patients with secondary multifocal osteonecrosis, the eNOS T-786C polymorphism was present in nine of twenty-two alleles compared with eight of forty-four alleles in twenty-two normal control subjects (risk ratio = 2.3; 95% confidence interval, 1.0 to 5.0; p = 0.047, Bp = 0.016). The frequency of homocystinemia (>13.5 mumol/L) was higher in patients with idiopathic multifocal osteonecrosis (two of thirteen patients) than in normal controls (none of fifty-one) (p = 0.039, Bp = 0.004). A high level of factor VIII (>150%) was seen in four of eight patients with idiopathic multifocal osteonecrosis and in seven of forty-eight normal controls (risk ratio = 3.4; 95% confidence interval, 1.3 to 9.1; p = 0.04, Bp = 0.008). The eNOS T-786C mutant allele was present in seven of twelve alleles in the six patients with idiopathic multifocal osteonecrosis who were tested, compared with twenty-five of 108 alleles in fifty-four control subjects (risk ratio = 2.5; 95% confidence interval, 1.4 to 4.5; p = 0.015, Bp = 0.008).

CONCLUSIONS

Limited by the small numbers of patients with multifocal osteonecrosis, this exploratory study suggested that thrombophilia was associated with both idiopathic multifocal osteonecrosis and secondary multifocal osteonecrosis, as was the eNOS T-786C polymorphism. Multifocal and unifocal osteonecrosis are similarly associated with thrombophilia, hypofibrinolysis, and the eNOS T-786C polymorphism, which are potentially treatable pathophysiologic conditions, requiring further study.

Osteonecrosis of the femoral head following an electrical injury to the leg

We report a case of osteonecrosis of the femoral head in a young man who is a carrier of the prothrombin gene mutation. We suggest that an electrical injury to his lower limb may have triggered intravascular thrombosis as a result of this mutation with subsequent osteonecrosis of the femoral head. No case of osteonecrosis of the femoral head secondary to a distant electrical injury has previously been reported.

Updates on bisphosphonates and potential pathobiology of bisphosphonate-induced jaw osteonecrosis

Osteonecrosis of the jaws is a major complication associated with long-term use of bisphosphonates. While osteonecrosis can arise from other precipitating conditions, bisphosphonate-induced jaw osteonecrosis (BJON) is highly associated with long-term administration of pamidronate (Aredia) and zoledronic acid (Zometa), which are two intravenous bisphosphonate formulations. The underlying pathogenesis of BJON and its site-specific presentation still remain to be fully elucidated. This review will discuss clinically available bisphosphonates, current opinions, pathogenesis, and management guidelines for bisphosphonate-induced jaw osteonecrosis.

Legg-Calve-Perthes disease, venous and arterial thrombi, and the factor V Leiden mutation in a four-generation kindred

In a 4-generation kindred identified through a 12-year-old female proband with Legg-Calve-Perthes Disease (LCPD) who was found to be heterozygous for the G1691A factor V Leiden mutation (FV), our specific aim was to assess associations of FV with LCPD and with venous and arterial thrombotic events. Despite lethal thromboembolism in 3 family members at ages 21, 35, and 38, retinal artery thrombosis, and deep venous thrombosis, no family members had previously been studied for the FV mutation until kindred screening-genetic counseling was prompted by the discovery of the FV mutation in a child proband with LCPD.

METHODS

In a 4-generation kindred identified through a 12-year-old female proband with LCPD and found to be heterozygous for the FV mutation, we assessed the FV genotype and its association with thromboembolism in 14 of 16 living first- and second-degree relatives.

RESULTS

There was 3-generation vertical and horizontal transmission of heterozygosity for the FV mutation. Of 14 living first- and second-degree relatives, 10 were heterozygous for the FV mutation, including the proband's sister, mother, and maternal grandmother. Of the 14 living relatives, 2 had thrombotic events (retinal artery thrombosis and deep venous thrombosis of the leg). The proband's maternal great-grandfather had a lethal pulmonary embolus at age 35, as did her maternal great aunt at age 38, and a female third cousin at age 21.

CONCLUSIONS

In a large kindred identified by a child with LCPD who was found to have the FV mutation, FV heterozygosity was found in 3 generations of previously undiagnosed family members and was associated with venous and arterial thrombosis throughout the kindred. We suggest that FV mutation be studied in children with LCPD facilitate diagnosis and genetic counseling for thrombophilia in their parents, siblings, and other kindred members, and because the proband LCPD child with the FV mutation is at increased risk for other thromboembolic abnormalities as an adult.

LEVEL OF EVIDENCE

1.

Endothelial nitric oxide synthase gene polymorphisms in patients with nontraumatic femoral head osteonecrosis

As endothelial nitric oxide synthase (eNOS) has beneficial effects on skeletal, vascular, and thrombotic systems, the association between nontraumatic femoral head osteonecrosis (FHON) and eNOS gene polymorphisms was investigated in Korean patients with FHON. Genomic DNA from 103 patients with nontraumatic FHON (idiopathic in 50, steroid-induced in 29, and alcohol abuse in 24) and 103 control subjects matched for gender and age (3-year range) was analyzed for the 27-bp repeat polymorphism in intron 4 and Glu298Asp polymorphism in exon 7. The frequencies of alleles and genotypes were compared between patients and control subjects. The frequency of 4a allele was significantly higher in total patients than control subjects [6.8% vs. 2.4%, p = 0.0345, odds ratio (OR) 2.931]. In subgroup analysis, the 4a allele significantly increased in patients with idiopathic FHON versus control subjects (9.0% vs. 2.4%, p = 0.0297, OR 3.976). The frequency of the 4a/b genotype in total patients (13.6% vs. 4.9%, p = 0.0302, OR 3.083) as well as patients with idiopathic FHON (18.0% vs. 4.9%, p = 0.0246, OR 4.302) was higher than control subjects. The distribution of Glu298Asp polymorphisms was not significantly different between patients and control subjects. Microstellate polymorphism in intron 4 of eNOS polymorphism was significantly associated with idiopathic FHON in Korean patients. Because 4a allele is associated with lower synthesis of eNOS, these results suggest that carrier state of 4a allele in intron 4 might be a genetic risk factor of FHON and could provide insight into the protective role of nitric oxide in the pathogenesis of FHON.

Association of corticosteroids and factor V, prothrombin, and MTHFR gene mutations with avascular osteonecrosis in renal allograft recipients

The mechanism of posttransplantation avascular osteonecrosis (AVN) is controversial. Besides an increased bone marrow pressure due to reduced blood supply, enhanced coagulation has been considered. We investigated the associations of factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations as well as cumulative corticosteroid doses with AVN in renal allograft recipients. The records of 39 volunteer patients and 11 patients in whom osteonecrosis was previously identified were reviewed for cumulative corticosteroid dosages during the first year. All patients were screened for factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations by direct sequencing of genomic DNA. The cumulative corticosteroid dosages at 3, 6, and 12 months in the osteonecrotic group (5033.5 +/- 1565.3, 7164.9 +/- 2063.1, 8835.1 +/- 2216.8 mg) were significantly higher than in the control group (3629 +/- 1504.1, 4784.5 +/- 1568.7, 6322.4 +/- 1686.6 mg; P = .013, P = .001, P = .001, respectively). No significant difference in factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations was observed between the osteonecrotic and control groups (P > .05). In conclusion, an association between the first year (3, 6, and 12 month) cumulative corticosteroid dosages and AVN was demonstrated in renal transplant recipients. However, no correlation was determined between factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations and osteonecrosis.

Expression of the angiomatrix and angiogenic proteins CYR61, CTGF, and VEGF in osteonecrosis of the femoral head

Angiogenesis and bone repair are closely linked processes. VEGF, CYR61, and CTGF have been identified as signaling factors that control angiogenesis and could be important in fracture healing. The purpose of this study was to investigate the expression of these signaling factors in osteonecrosis of the femoral head. Twenty-one bone cylinders were retrieved from hips of patients with osteonecrosis of the femoral head at different ARCO stages. Immunohistochemistry for CD34, CYR61, CTGF, and VEGF expression was done on each bone cylinder representing the different regions of osteonecrosis (necrosis, fibrosis, transition zone, and edematous area). VEGF, CYR61, and CTGF were expressed in samples with osteonecrosis. Particularly VEGF and CYR61 were highly expressed in the edematous area. CYR61 was also highly expressed in the transition zone. CTGF was expressed mainly in the area of marrow fibrosis and edema. CYR61, CTGF, and VEGF are expressed to different degrees in the different repair zones of osteonecrosis. Particularly, the high expression of VEGF and CYR61 in the edematous area may represent a consequence of hypoxia and indicate a role of these proteins in the repair processes ongoing in osteonecrosis.

Changes in coagulation and fibrinolysis of post-SARS osteonecrosis in a Chinese population

The purpose of this study was to detect changes in coagulation and fibrinolysis of post-severe acute respiratory syndrome (SARS) Chinese patients with osteonecrosis, investigate the aetiology of post-SARS osteonecrosis (ON), and select the sensitive molecular markers for identifying the susceptible population. For this study, blood samples were collected from 88 patients with post-SARS ON and 52 healthy people. Activated partial thromboplastin time (APTT), protein C (PC), antithrombin III (AT-III), plasminogen activator inhibitor (PAI), activated protein C resistance (APC-R), plasminogen (PLG), von Willebrand's factor(vWF), D-dimer (D-D), fibrinogen (Fib), and homocysteine (HCY) were examined by enzyme-linked immunosorbent assay (ELISA). We noted that blood agents of patients with ON changed obviously. APTT, PC, AT-III, PAI, APC-R, and PLG were significantly different between the two groups. Hypercoagulation and hypofibrinolysis were found in patients with post-SARS ON. Therefore, these examinations can be used to screen a population susceptible to ON. Measurements of APTT, PC, AT-III, PAI, APC-R, and PLG are sensitive blood tests for screening purposes.