Debarti Ray

Prevalence of vitamin D deficiency and its relationship with thyroid autoimmunity in Asian Indians: a community-based survey.

25-Hydroxy vitamin D (25(OH)D) deficiency is linked with predisposition to autoimmune type 1 diabetes and multiple sclerosis. Our objective was to assess the relationship between serum 25(OH)D levels and thyroid autoimmunity. Subjects included students, teachers and staff aged 16-60 years (total 642, 244 males, 398 females). Serum free thyroxine, thyroid-stimulating hormone (TSH), and thyroid peroxidase autoantibodies (TPOAb), intact parathyroid hormone and 25(OH)D were measured by electrochemiluminescence and RIA, respectively. Thyroid dysfunction was defined if (1) serum TSH > or = 5 microU/ml and TPOAb>34 IU/ml or (2) TSH > or = 10 microU/ml but normal TPOAb. The mean serum 25(OH)D of the study subjects was 17.5 (sd 10.2) nmol/l with 87 % having values < or = 25 nmol/l. TPOAb positivity was observed in 21 % of subjects. The relationship between 25(OH)D and TPOAb was assessed with and without controlling for age and showed significant inverse correlation (r - 0.08, P = 0.04) when adjusted for age. The prevalence of TPOAb and thyroid dysfunction were comparable between subjects stratified according to serum 25(OH)D into two groups either at cut-off of < or = 25 or >25 nmol/l or first and second tertiles. Serum 25(OH)D values show only weak inverse correlation with TPOAb titres. The presence of such weak association and narrow range of serum 25(OH)D did not allow us to interpret the present results in terms of quantitative cut-off values of serum 25(OH)D. Further studies in vitamin D-sufficient populations with wider range of serum 25(OH)D levels are required to substantiate the findings of the current study.

Pattern of 25-hydroxy vitamin D response at short (2 month) and long (1 year) interval after 8 weeks of oral supplementation with cholecalciferol in Asian Indians with chronic hypovitaminosis D

Hypovitaminosis D is common in Asian Indians. Physicians often prescribe 1500 mug (60 000 IU) cholecalciferol per week for 8 weeks for vitamin D deficiency in India. Its efficacy to increase serum 25-hydroxy vitamin D (25(OH)D) over short (2 months) and long (1 year) term is not known. We supplemented a group of twenty-eight apparently healthy Asian Indians detected to have low serum 25(OH)D (mean 13.5 (sd 3.0) nmol/l) on screening during January-March 2005. Serum parathyroid hormone (PTH) level was supranormal in 30 % of them. Oral supplementation included 1500 mug cholecalciferol per week and 1g elemental Ca daily for 8 weeks. Serum 25(OH)D, total Ca, inorganic P and intact (i) PTH were reassessed in twenty-three subjects (twelve females and eleven males) who had follow up at both 8 weeks and 1 year. At 8 weeks the mean 25(OH)D levels increased to 82.4 (sd 20.7) nmol/l and serum PTH normalized in all. Twenty-two of the twenty-three subjects had 25(OH)D levels>49.9 nmol/l. At 1 year, though the mean 25(OH)D level of 24.7 (sd 10.9) nmol/l was significantly higher than the baseline, all subjects were 25(OH)D deficient. Five subjects with supranormal iPTH at baseline showed recurrence of biochemical hyperparathyroidism. Thus, with 8 weeks of cholecalciferol supplementation in Asian Indians with chronic hypovitaminosis D, mean serum 25(OH)D levels would be normalized and serum PTH value would be reduced to half. However, such quick supplementation would not maintain their 25(OH)D levels in the sufficient range for 1 year. For sustained improvement in 25(OH)D levels vitamin D supplementation has to be ongoing after the initial cholecalciferol loading.

Presence of spondyloarthropathy and its clinical profile in patients with hypoparathyroidism.

Background  Though spondyloarthropathy has been described in patients with sporadic idiopathic hypoparathyroidism (SIH), the clinical profile is not known.

Polymorphisms at +49A/G and CT60 sites in the 3′ UTR of the CTLA-4 gene and APECED-related AIRE gene mutations analysis in sporadic idiopathic hypoparathyroidism

Autoimmune diseases such as Graves’ disease and type 1 diabetes have been linked with +49A/G and CT60 single nucleotide polymorphisms (SNPs) in the 3′ UTR of the cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4) gene. Both these SNPs are functionally relevant and linked with T‐lymphocyte activation. Hypoparathyroidism is seen in 70% of patients with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome (APECED). Although calcium sensing receptor autoantibodies (CaSRAb) and generalized activation of T lymphocytes are reported among patients with sporadic idiopathic hypoparathyroidism (SIH), CTLA‐4 gene SNPs and APECED‐related autoimmune regulator (AIRE) gene mutations have not been assessed in them. We studied lead CTLA‐4 gene SNPs and APECED‐related AIRE gene mutations in 73 patients with SIH and 114 healthy subjects. The CTLA‐4 gene SNPs +49A/G in exon 1, CT60A/G in 3′ UTR and −318C/T in the promoter region were genotyped by polymerase chain reaction‐restriction fragment‐length polymorphism (PCR‐RFLP) using BstEII, NcoI and MseI endonucleases, respectively. The APECED‐related AIRE gene mutations, which is R257X (Finn‐major) in exon 6, 4‐bp insertion and 13‐bp deletion in exon 8, and Iranian Jews population ‘Y85C’ mutation in exon 2, were studied by PCR‐RFLP (Taq‐I), PCR and nucleotide sequencing, respectively. CaSRAb were studied by immunoblotting. The frequencies of CTLA‐4 A/A49, A/G49 and G/G49 genotypes in the patients (47.9%, 38.4% and 13.7%) and controls (45.6%, 39.5% and 14.9%, respectively) and the frequencies of CT60 A/A, A/G, and G/G genotypes in the patient (42.4%, 37.0% and 20.6%) and the control (38.6%, 40.4% and 21.0%, respectively) groups were not significantly different. The frequencies of various haplotypes including genetic loci +49A/G and CT60 and frequencies of G alleles at these positions were comparable between patient and the control groups and its presence did not correlate with clinical and biochemical indices of the disease. None of the patients had APECED‐related AIRE gene mutations. Lack of significant difference in the pattern of CTLA‐4 A/G49 and/or CT60A/G genotypes and absence of common APECED syndrome‐related AIRE gene mutations among patients and controls suggest that these sites do not play a role in the development of the SIH.

Predisposition to vitamin D deficiency osteomalacia and rickets in females is linked to their 25(OH)D and calcium intake rather than vitamin D receptor gene polymorphism

Background   Osteomalacia (OSM) and rickets are widely prevalent in developing countries especially in females. The factors associated with such predisposition are not known.

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene R620W variant and sporadic idiopathic hypoparathyroidism in Asian Indians

Recently, a gain of function variant C1858T of the lymphoid‐specific protein tyrosine phosphatase non‐receptor (LYP, PTPN22) gene has been reported to be associated with several autoimmune disorders including Graves’ disease, type 1 diabetes, rheumatoid arthritis and vitiligo. The present study was carried out in 80 patients with sporadic idiopathic hypoparathyroidism (SIH) [43 males and 37 females, mean ± SD age and duration of symptoms 32.5 ± 14.1 years and 6.7 ± 7.2 years (range 1 day to 35 years), respectively] and 193 healthy controls (male : female ratio 91:102, mean ± SD age, 43.1 ± 11.6 years) to assess association of 1858T allele with the disease. Polymerase chain reaction–restriction fragment length polymorphism analysis was performed to genotype C1858T variant. The frequency of occurrence of 1858T allele was 4/160 (2.5%) in SIH and 5/386 (1.3%) in the control alleles (odds ratio 1.95, 95% CI 0.51–7.37). Thus, the present study reveals that 1858T allele is rare (1.3%) in Asian Indians. The trend of higher prevalence of 1858T allele in patients with SIH needs to be studied further in other population with higher rate of the allele to support the autoimmune basis of the disease.

Absence of pathogenic calcium sensing receptor mutations in sporadic idiopathic hypoparathyroidism

Background  Sporadic idiopathic hypoparathyroidism (SIH) is the most common cause of hypoparathyroidism. While calcium sensing receptor (CaSR) autoantibodies are observed in 49% of cases, aetiopathogenetic mechanisms in others are under investigation. Mutations in the PTH gene including its 3′ untranslated region, autoimmune regulator gene and lead CTLA‐4 gene single nucleotide polymorphism (SNPs) are not associated with the disease. There are reports of de novo activating mutations of the CaSR gene in a few patients with SIH.

Presence of 25(OH)D deficiency and its effect on vitamin D receptor mRNA expression

Background and objectives:Vitamin D and its metabolites act through vitamin D receptor (VDR). We hypothesized that subjects with low serum 25(OH)D levels but normal PTH might have increased VDR expression.Design and Methods:VDRmRNA expression was assessed by real time PCR in duodenal mucosa and PBMC (peripheral blood mononuclear cells) in 45 subjects with normal duodenoscopy and in PBMC alone in 48 healthy volunteers with hypovitaminosis D. 25(OH)D, PTH and VDRmRNA expression in PBMC was reassessed after 8 weeks of oral cholecalciferol (60 000 IU per week) in a subset (n=23) of healthy volunteers.Results and Conclusions:The VDRmRNA expressions in the duodenum and PBMC were significantly correlated (r=0.42), but the expression was 13 times higher in the former than the latter. The mean VDRmRNA expression was similar in 25(OH)D-deficient subjects with or without PTH elevation, both in the duodenum and PBMC. The PBMC VDRmRNA expression showed no significant change after cholecalciferol supplementation. A weak correlation coefficient between duodenal mucosa and PBMC VDRmRNA suggests that caution needs to be exercised while using the latter as a surrogate for other sites.