The distribution of group-specific component (Gc) subtypes was determined by isoelectric focussing in thin layer polyacrylamide gels of pH range 4 to 6.5, in a group of 2412 individuals from 10 Mongoloid populations of East Asia. The sample comprised 959 Chinese from different localities (Singapore, 249; Malaysia, 347; Taiwan, 246; Hong Kong, 57; Fuzhou mainland, 60), 338 Koreans, 277 Filipinos, 484 Thais, 330 Malays and 24 Indonesians. The Filipinos and Malays had lower frequencies of Gc2 (0.15 and 0.18) compared to other Mongoloid populations (0.23 to 0.32) and the Chinese (0.24 to 0.32). The frequencies of Gc1F varied from 0.39 to 0.49 in the Chinese and 0.35 to 0.52 in other Mongoloid populations. Low frequency of rarer variants was observed in most of the populations. The average frequency of Gc2 was higher in the Japanese (0.26 +/- 0.01) than in the Chinese (0.24 +/- 0.02), and in Mongoloids of East Asia (0.23 +/- 0.01) and South-East Asia (0.17 +/- 0.01). The average frequencies of Gc1F and Gc1S were similar in the Chinese and Japanese, whereas the Mongoloids of South-East Asia had a much higher frequency of Gc1F and a lower frequency of Gc1S than the Chinese, Japanese and East Asian Mongoloid populations.
INTRODUCTION: Low 25-hydroxyvitamin D [25(OH)D] levels have not been consistently associated with bone mineral density (BMD). It has been suggested that calculation of the free/bioavailable 25(OH)D may correlate better with BMD. We examined this hypothesis in a cohort of Malaysian women.
MATERIALS AND METHODS: A cross-sectional study of 77 patients with rheumatoid arthritis (RA) and 29 controls was performed. Serum 25(OH)D was measured using the Roche Cobas E170 immunoassay. Serum vitamin D binding protein (VDBP) was measured using a monoclonal enzyme-linked immunosorbent assay (ELISA). Free/bioavailable 25(OH)D were calculated using both the modified Vermuelen and Bikle formulae.
RESULTS: Since there were no significant differences between RA patients and controls for VDBP and 25(OH)D, the dataset was analysed as a whole. Calculated free 25(OH)D by Vermeulen was strongly correlated with Bikle (r = 1.00, p < 0.001). A significant positive correlation was noted between measured total 25(OH)D with free/bioavailable 25(OH)D (r = 0.607, r = 0.637, respectively, p < 0.001). Median free/bioavailable 25(OH)D values were significantly higher in Chinese compared with Malays and Indians, consistent with their median total 25(OH)D. Similar to total 25(OH)D, the free/bioavailable 25(OH)D did not correlate with BMD.
CONCLUSION: In this first study of a multiethnic female Malaysian population, free/bioavailable 25(OH)D were found to reflect total 25(OH)D, and was not superior to total 25(OH)D in its correlation with BMD. Should they need to be calculated, the Bikle formula is easier to use but only calculates free 25(OH)D. The Vermuelen formula calculates both free/bioavailable 25(OH)D but is more complex to use.
We have developed the methodologies for typing and family studies to establish the modes of inheritance of water buffalo red cell acid phosphatase (Acp), protease inhibitor (Pi), and group-specific component (Gc) on isoelectric focusing and albumin (Alb), red cell alpha-esterase-3 (Est-3), and catalase (Cat) on polyacrylamide gel electrophoresis. Family studies showed that Pi, Gc, Alb, and Cat are coded by autosomal genes with two codominant alleles, while Est-3 is autosomal with two codominant alleles and a recessive null allele and Acp exhibits three codominant alleles.
AIM: Vitamin D3 [25(OH)D] has been shown to be important in bone health and can influence rheumatoid arthritis (RA) disease activity. Vitamin D-binding protein (VDBP) levels vary with race and may modulate 'bioavailable' levels of 25(OH)D. The aim of this study was to explore the relationships between 25(OH)D, VDBP and clinical factors on bone mineral density (BMD) in a group of multi-ethnic Malaysian RA patients and healthy controls.
METHODS: A cross-sectional study of 77 female RA patients and 29 controls was performed. Serum 25(OH)D was measured using the Elecsys® Vitamin D total assay. Serum VDBP was measured using a Quantikine® enzyme-linked immunosorbent assay kit. BMD was assessed using dual-energy X-ray absorptiometry (DXA).
RESULTS: Overall, mean 25(OH)D levels were 42.66 ± 21.75 nmol/L with no significant difference between RA patients and controls. 25(OH)D levels were significantly higher in Chinese, compared to Malay/Indian subjects. In RA patients, menopausal status and body mass index (BMI) were significantly associated with BMD but not 25(OH)D or RA Disease Activity Score of 28 joints (DAS28). There was no significant correlation between 25(OH)D and DAS28, even after correction for menopausal status and BMI. VDBP levels were not significantly different between the races and did not significantly correlate with BMD, 25(OH)D overall, or DAS28 in RA patients.
CONCLUSIONS: In Malaysian RA patients, menopausal status and BMI were more important influences on BMD than 25(OH)D or RA disease activity. The utility of measuring VDBP levels in this population remains uncertain.
Study site: Rheumatology clinic, Hospital Tuanku Jaafar, Seremban, Negeri Semblance; Klinik Pakar Puchong, Puchong, Kuala Lumpur, Malaysia