Meng Xw

Three Novel Mutations of the PHEX Gene in Three Chinese Families with X-linked Dominant Hypophosphatemic Rickets

X-linked dominant hypophosphatemia (XLH, OMIM307800), the most prevalent form of inherited rickets in humans, is a dominant disorder of phosphate homeostasis characterized by growth retardation, rachitic and osteomalacic bone disease, hypophosphatemia, and renal phosphate wasting. The gene responsible for XLH was identified by positional cloning and designated PHEX (formerly PEX) to depict a phosphate-regulating gene homologous with endopeptidases on the X chromosome. Recently, extensive mutation analysis of the PHEX gene has revealed a wide variety of gene defects in XLH. The ethnic distribution of the mutations is very widespread but only a few mutations in Chinese have been reported. To analyze the molecular basis in three unrelated Chinese families with XLH, we determined the nucleotide sequence of the PHEX gene and fibroblast growth factor 23 (FGF23) gene of affected members. The serum FGF23 concentrations of these patients with XLH were also measured. Three different novel mutations were observed in these three families: one deletion mutation c.264delG causing p.W88 X; one missense mutation c.1673C>G causing p.P558A; one nonsense mutation c.1809G>A causing p.W603 X. Serum concentration of FGF23 in XLH patients of these three families was significantly higher than normal. The results suggest that PHEX gene mutations were responsible for XLH in these patients and these mutations may contribute to a higher serum FGF23 level.

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.

Germinal mosaicism of GATA3 in a family with HDR syndrome

Germinal Mosaicism of GATA3 in a Family With HDR Syndrome Yue Sun, Weibo Xia,* Xiaoping Xing, Mei Li, Ou Wang, Yan Jiang, Yu Pei, Ping Ye, Huaicheng Liu, Yingying Hu, Xunwu Meng, and Xueying Zhou Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China Department of Endocrinology, Second Artillery Forces General Hospital, People’s Liberation Army, Beijing, China Dalian Red Cross Blood Center, Dalian, Liaoning Province, China