Genome-wide meta-analysis reveals novel susceptibility loci for thyrotoxic periodic paralysis.

OBJECTIVE: Thyrotoxic periodic paralysis (TPP) is a rare and potentially fatal complication of hyperthyroidism. By meta-analysis of genome-wide association studies, we aim to discover novel susceptibility loci and understand the pathogenesis of TPP. METHODS: This meta-analysis comprised 319 TPP cases and 3516 healthy controls from three independent cohorts (two from Hong Kong; one from Shanghai). Genetic variants in each cohort were separately genotyped, imputed and analyzed for association with TPP. Fixed-effect meta-analysis was performed to combine the data. Using the three independent genome-wide significant variants, a weighted genetic risk score (GRS) was developed. RESULTS: Of 7 077 246 variants tested for association with TPP, 260 variants reached genome-wide significance and were represented by independent variants from four distinct genomic loci, but a risk locus for Graves' disease at 6p21.33-p21.22 was excluded from subsequent analyses. Two novel loci near TRIM2 (4q31.3; rs6827197: OR = 4.075; P = 3.46 × 10-9) and AC140912.1 (16q22.3; rs6420387: OR = 1.861; P = 2.66 × 10-8) were identified. Together with previously reported KCNJ2 (17q24.3; rs312743: OR = 2.564; P = 1.15 × 10-21), the three susceptibility variants explained 4.36% of the genetic liability. Expression quantitative trait loci analyses showed the variants altered expression of TRIM2 in nerve and KCNJ2 in skeletal muscle. The weighted GRS had an area under curve of 0.827 and 0.682 in the derivation and validation cohorts in Hong Kong. CONCLUSIONS: We identified two novel TPP risk loci near TRIM2 and AC140912.1. While rare mutations in TRIM2 and KCNJ2 were implicated in monogenic disorders characterized by muscle paralysis, our study suggested common variants near these genes might dysregulate gene expression and lead to milder phenotypes.

Efficacy and safety of 2 g/day of strontium ranelate in Asian women with postmenopausal osteoporosis.

Strontium ranelate is a new effective anti-osteoporotic treatment having a unique mode of action, reducing bone resorption while promoting continued bone formation, with a broad range of anti-fracture efficacy at vertebral as well as peripheral sites. In Phase III studies, it has proven its early and sustained efficacy against vertebral fractures in Caucasians along with a significant increase in lumbar bone mineral density (BMD). The aim of this randomized double-blind study was to demonstrate the efficacy of strontium ranelate (2 g/day) on lumbar spine bone mineral density and the clinical and biological safety in Asian postmenopausal osteoporotic patients compared to placebo over 1 year. Three hundred and twenty-nine eligible women from mainland China, Hong Kong and Malaysia were randomized into the study. The baseline characteristics were similar in the treatment and placebo groups: mean age of 66.2+/-6.5 years, time since menopause 17.6+/-7.2 years. In the Full Analysis Set (FAS, N=302), the mean baseline lumbar L2-L4 BMD was 0.715+/-0.106 g/cm(2) in the strontium ranelate group and 0.708 +/- 0.109 g/cm2 in the placebo group. The mean baseline femoral neck BMD was 0.575+/-0.074 g/cm2 and 0.566+/-0.069 g/cm2 respectively and mean total hip BMD was 0.642+/-0.080 g/cm2 and 0.631 +/-0.088 g/cm2 respectively. The overall compliance was 91.4% in the study drug group, and 97.4% in the placebo group. After 1 year of treatment, the lumbar spine, femoral neck and total hip BMD in the treated group was significantly increased by 3-5% as compared to placebo. Strontium ranelate was well tolerated. The most frequently reported emergent adverse events were comparable in both groups (60.4% versus 60.0%), with majority of them being mild gastrointestinal disorders. There were no clinically relevant changes in laboratory tests, such as blood routine, hepatic and renal function. It is thus concluded that the effects of 2 g/day strontium ranelate on BMD and its safety profile in this cohort of postmenopausal osteoporotic Asian women were consistent with results obtained from Caucasian women in which the efficacy on the reduction in risk of fracture has been proven.