Arterial Calcification Due to Deficiency of CD73 (ACDC) As One of Rheumatic Diseases Associated With Periarticular Calcification.

In 2011, St Hilaire et al (N Engl J Med. 2011;364:432-442) identified mutations in the ecto-5'-nucleotidase (NT5E) gene, which encodes CD73, in members of 3 families with symptomatic arterial and joint calcifications. The deficiency of CD73 involves the extracellular adenosine metabolism that influences inorganic pyrophosphate and phosphate metabolism and leads to tissue calcification. Herein, we report an additional case with arterial calcification due to deficiency of CD73. Genetic analyses revealed that the patient was a compound heterozygote of mutations in the NT5E gene. The present case had intermittent monoarthritis of the finger joints and early-onset osteoarthritis in the hands. Occlusion of calcified peripheral arteries is the most important outcome of the disease. However, the rheumatic manifestations may be important clues to the diagnosis. Rheumatologists should recognize deficiency of CD73 as a rheumatic disease.

Effect of genetic polymorphisms on development of gout.

OBJECTIVE: To validate the association between genetic polymorphisms and gout in Japanese patients, and to investigate the cumulative effects of multiple genetic factors on the development of gout. METHODS: Subjects were 153 Japanese male patients with gout and 532 male controls. The genotypes of 11 polymorphisms in the 10 genes that have been indicated to be associated with serum uric acid levels or gout were determined. The cumulative effects of the genetic polymorphisms were investigated using a weighted genotype risk score (wGRS) based on the number of risk alleles and the OR for gout. A model to discriminate between patients with gout and controls was constructed by incorporating the wGRS and clinical factors. C statistics method was applied to evaluate the capability of the model to discriminate gout patients from controls. RESULTS: Seven polymorphisms were shown to be associated with gout. The mean wGRS was significantly higher in patients with gout (15.2 ± 2.01) compared to controls (13.4 ± 2.10; p < 0.0001). The C statistic for the model using genetic information alone was 0.72, while the C statistic was 0.81 for the full model that incorporated all genetic and clinical factors. CONCLUSION: Accumulation of multiple genetic factors is associated with the development of gout. A prediction model for gout that incorporates genetic and clinical factors may be useful for identifying individuals who are at risk of gout.

A Japanese Family Suffering from Familial Juvenile Hyperuricemic Nephropathy due to a Rare Mutation of the Uromodulin Gene.

We report the case of a Japanese family suffering from familial juvenile hyperuricemic nephropathy (FJHN) due to a rare missense mutation of the uromodulin (UMOD) gene. An 18-year-old male presented with gout, hyperuricemia, and stage 3 chronic kidney disease. Mostly, FJHN is caused by a mutation altering the cystine residue of UMOD/Tamm-Horsfall protein. However, in the present case, a T688C mutation was identified in exon 4, resulting in amino acid substitution with arginine replacing tryptophan at position 230 (Trp230Arg). This mutation was also found in his brother and father with the same phenotype, indicating autosomal dominant inheritance. The affected amino acid was conserved in 200 healthy Japanese controls. Therefore, mutation T688C most likely causes rare structural and/or functional abnormalities in UMOD/Tamm-Horsfall protein.

Associations between methotrexate treatment and methylenetetrahydrofolate reductase gene polymorphisms with incident fractures in Japanese female rheumatoid arthritis patients.

Several case reports have described associations between pathological nonvertebral fractures and low-dose methotrexate (MTX) in rheumatoid arthritis (RA) patients. Furthermore, a significant association between the C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene and incident fractures has been reported in postmenopausal women. We attempted to determine whether MTX use and MTHFR polymorphisms are associated with incident fracture risk in Japanese female RA patients. DNA samples, laboratory data, and clinical data were obtained from 731 female RA patients more than 50 years old as part of the Institute of Rheumatology Rheumatoid Arthritis (IORRA) observational cohort study. Genotyping of the MTHFR polymorphisms C677T and A1298C was performed using TaqMan SNP Genotyping Assays. MTX use, MTHFR polymorphisms, and other potential risk factors predictive of fracture were analyzed by Cox proportional hazards regression models, including time-dependent covariates. During 78 months from October 2000 to March 2007, 25 and 90 patients developed vertebral and nonvertebral fractures, respectively. Patients with nonvertebral fractures were more likely to take MTX (P = 0.011; odds ratio, 1.77; 95% confidence interval, 1.13-2.76) compared to patients without fractures. Although the C677T and A1298C polymorphisms were not significantly associated with incident fracture risk, MTX use, age, disease duration, and Japanese health assessment questionnaire score were significantly (P < 0.05) and independently associated with nonvertebral fracture incidence. Our results suggest that MTX use is associated with a nonvertebral fracture risk, whereas MTHFR polymorphism status does not appear to be a clinically useful marker for predicting fracture risk in Japanese female RA patients.