Investigating ANKH and ENPP1 in Slovakian families with chondrocalcinosis.

Familial articular chondrocalcinosis (CC) was first reported in 1963. It is characterised by multiple calcifications of hyaline and fibrous cartilage in the joints and intervertebral discs. Mutations in ANKH have been identified in several pedigrees as a monogenic cause for this disorder. ANKH is a key protein in pyrophosphate metabolism and is involved in pyrophosphate transport across the cell membrane. The objective of this work was to screen ANKH and ENPP1, two key genes in pyrophosphate metabolism, in Slovakian kindreds with familial CC. DNA samples from 25 individuals (10 affected, 15 unaffected) from 8 families were obtained. The promoter, coding regions and intron-exon boundaries of ANKH and ENPP1 were sequenced. Twelve DNA sequence variants, six in each gene, were identified. All the variants had been previously identified. None segregated with the disease. Our results suggest that neither ANKH nor ENPP1 mutations are the cause of CC in these families, indicating that possibly other major genes are involved in the aethiopathogenesis of this condition in these families.

Dose-response relationship between lower serum magnesium level and higher prevalence of knee chondrocalcinosis.

BACKGROUND: The aim was to assess serum magnesium levels in relation to prevalence of knee chondrocalcinosis in two population-based Chinese studies. METHODS: Data included in this analysis consisted of two population-based cross-sectional studies, i.e., the Xiangya Hospital Health Management Center Study and the Xiangya Osteoarthritis (XO) Study I. A bilateral knee anteroposterior radiograph was obtained from each subject. Radiographic knee chondrocalcinosis was present if there was definite linear cartilage calcification. Serum magnesium concentration was measured using the chemiluminescence method. We examined the relation of serum magnesium levels to prevalence of knee chondrocalcinosis using generalized estimating equations. RESULTS: The prevalence of knee chondrocalcinosis was 1.4% in the Xiangya Hospital Health Management Center Study (n = 12,631). Compared with the lowest tertile, the age, sex and body mass index (BMI)-adjusted odds ratios (ORs) of chondrocalcinosis were 0.59 (95% CI 0.40-0.87) and 0.49 (95% CI 0.33-0.72) in the second and the third tertiles of serum magnesium, respectively (P for trend <0.001). The prevalence of knee chondrocalcinosis in the XO Study I (n = 1316) was 4.1%. The age, sex and BMI-adjusted ORs of chondrocalcinosis were 0.67 (95% CI 0.34-1.30) in the second and 0.45 (95% CI 0.21-0.94) in the third tertile of serum magnesium when compared with the lowest tertile (P for trend = 0.030). Similar results were observed in men and women in both studies. Adjusting for additional potential confounders did not change the results materially. CONCLUSIONS: Subjects with lower levels of serum magnesium, even within the normal range, had higher prevalence of knee chondrocalcinosis in a dose-response relationship manner, suggesting that magnesium may have a preventive or therapeutic potential for knee chondrocalcinosis.

HLA-antigens in a Tunisian familial chondrocalcinosis.

Thirty members of a Tunisian family with hereditary chondrocalcinosis were typed for HLA-A, B, and DR antigens: 7 affected and 23 unaffected subjects in three consecutive generations. The haplotype A1 B12 DR3 was found in all affected subjects and in 8 unaffected members. Chondrocalcinosis in this family may be associated with the haplotype A1 B12 DR3. The mode of transmission was autosomal dominant with incomplete penetrance.

Lower prevalence of chondrocalcinosis in Chinese subjects in Beijing than in white subjects in the United States: the Beijing Osteoarthritis Study.

OBJECTIVE: Chondrocalcinosis, which can promote joint inflammation and cartilage degeneration, is highly prevalent in elderly white subjects. Data on its prevalence are scarce in other ethnic populations. This study was undertaken to compare the prevalence of chondrocalcinosis in Chinese subjects with that in white subjects. METHODS: We recruited a random sample of Beijing residents ages >or=60 years. Participants underwent standard weight-bearing anteroposterior knee radiography and posteroanterior hand radiography using the protocols developed in the Framingham Osteoarthritis Study. Radiographic chondrocalcinosis was defined as present in a knee or wrist when there was evidence of definite linear cartilage calcification. We compared the prevalence of chondrocalcinosis in Chinese subjects with that in white subjects using age-standardized prevalence ratios. We used identical methods to collect samples of tap water from 2 cities and measured their levels of calcium, magnesium, and phosphate in the same laboratory. RESULTS: Chinese subjects had a much lower prevalence of knee chondrocalcinosis (1.8% in men, 2.7% in women) than did white subjects (6.2% in men, 7.7% in women), with the age-standardized prevalence ratio being 0.34 (95% confidence interval [95% CI] 0.20-0.54) and 0.43 (95% CI 0.31-0.59) in men and women, respectively. Wrist chondrocalcinosis was rare in elderly Chinese subjects (prevalence 0.3% in men and 1.0% in women), with the age-standardized prevalence ratio being 0.06 (95% CI 0.01-0.18) in Chinese men and 0.18 (95% CI 0.10-0.30) in Chinese women. Calcium levels in the tap water in Beijing were 15-fold higher than in Framingham, whereas no difference was found in magnesium and phosphate levels. CONCLUSION: Knee chondrocalcinosis and wrist chondrocalcinosis are far less common in Chinese subjects in Beijing than in US white subjects in Framingham, Massachusetts. Given the current lack of understanding of the etiology of chondrocalcinosis, further epidemiologic studies of the impact of genetic and environmental factors on occurrence of chondrocalcinosis are indicated.