Mutational analysis of PHEX, FGF23 and DMP1 in a cohort of patients with hypophosphatemic rickets

Background X‐linked hypophosphatemic rickets, autosomal dominant hypophosphatemic rickets and autosomal recessive hypophosphatemic rickets make up a group of renal phosphate wasting disorders with common clinical and biochemical characteristics. These three types of rickets are related to mutations in PHEX, FGF23 and dentin matrix protein 1 (DMP1), respectively. Objective The objective of the study was to evaluate the frequency of mutations that occur in these three genes associated with hypophosphatemic rickets. Patients and Methods In this study, we sequenced these genes in 76 members of 46 kindreds from a large hypophosphatemic rickets cohort. Results Forty‐two individuals from 27 kindreds were found to have mutations in PHEX; 16 of which were novel. One subject had an FGF23 mutation. No individuals were found to have mutations in DMP1 consistent with the presence of recessive hypophosphatemic rickets. Conclusions Our data highlight the wide spectrum of genetic variation that can be seen in PHEX, FGF23 and DMP1 when screening a large cohort with hypophosphatemic rickets.     

High-dose fast infusion of parenteral iron isomaltoside is efficacious in inflammatory bowel disease patients with iron-deficiency anaemia without profound changes in phosphate or fibroblast growth factor 23

Objective: Iron isomaltoside (Monofer^®) is a high-dose intravenous iron preparation with good tolerability and efficacy in inflammatory bowel disease (IBD) patients with iron deficiency anaemia (IDA). This trial evaluates the safety and efficacy, including effect on intact fibroblast growth factor 23 (iFGF23) of a high single dose and cumulative doses of iron isomaltoside in IBD patients with IDA.

Materials and methods: The trial was a prospective, open-label, multi-centre trial conducted in IBD patients with IDA. Based upon haemoglobin (Hb) levels at baseline and weight, the patients received 1500, 2000, 2500 or 3000?mg of iron isomaltoside infused in single doses up to 2000?mg. The outcome measurements included adverse drug reactions (ADRs) and changes in haematology and biochemistry parameters.

Results: Twenty-one IBD patients with IDA were enrolled, receiving 1500 (seven patients), 2000 (eight patients), 2500?mg (four patients) or 3000 (two patients) mg of iron. No serious ADRs were observed. Four patients experienced nine mild to moderate ADRs (hypersensitivity, pyrexia, vomiting, constipation, abdominal pain, dyspepsia (two events) and eye allergy (two events)). In total, 15 (75%) patients had an increase in Hb of ≥2.0?g/dL during the trial, with normalisation of ferritin. No changes in iFGF23 or clinically significant hypophosphataemia were found.

Conclusion: Rapid infusions of high-dose iron isomaltoside, administered as single doses up to 2000?mg and cumulative doses up to 3000?mg, were without safety concerns and were efficacious in increasing Hb levels in IBD patients. Iron isomaltoside did not induce profound phosphate wasting via increased iFGF23 levels.     

Mutational analysis and genotype-phenotype correlation of the PHEX gene in X-linked hypophosphatemic rickets

PHEX is the gene defective in X-linked hypophosphatemic rickets. In this study, analysis of PHEX revealed mutations in 22 hypophosphatemic rickets patients, including 16 of 28 patients in whom all 22 PHEX exons were studied. In 13 patients, in whom no PHEX mutation had been previously detected in 17 exons, the remaining 5 PHEX exons were analyzed and mutations found in 6 patients. Twenty different mutations were identified, including 16 mutations predicted to truncate PHEX and 4 missense mutations. Phenotype analysis was performed on 31 hypophosphatemic rickets patients with PHEX mutations, including the 22 patients identified in this study, 9 patients previously identified, and affected family members. No correlation was found between the severity of disease and the type or location of the mutation. However, among patients with a family history of hypophosphatemic rickets, there was a trend toward more severe skeletal disease in patients with truncating mutations. Family members in more recent generations had a milder phenotype. Postpubertal males had a more severe dental phenotype. In conclusion, although identifying mutations in PHEX may have limited prognostic value, genetic testing may be useful for the early identification and treatment of affected individuals. Furthermore, this study suggests that other genes and environmental factors affect the severity of hypophosphatemic rickets.     

罗钙全与磷酸盐合剂治疗X-连锁低磷性佝偻病的剂量探讨

对４２例１个月至１２岁健康儿童（Ｃ组）及９例２－１１岁Ｘ－连锁低磷性佝偻病（ＸＬＨＲ）患儿,于治疗前后采用全自动生化分析仪测定其血钙（Ｃａ）、磷（Ｐ）、碱性磷酸酶（ＡＬＰ）,并计算其钙磷乘积。将ＸＬＨＲ患儿分为Ａ、Ｂ两组,Ａ组采用传统治疗,主要给予中性磷酸盐合剂,辅以维生素Ｄ制剂不规则治疗;Ｂ组联合给予罗钙全「１,２５（ＯＨ）２Ｄ３」及磷酸盐合剂规则治疗;两观察时间为３￣１２个月。结果显示,Ａ、Ｂ     

TP53 mutations in myelodysplastic syndrome are strongly correlated with aberrations of chromosome 5, and correlate with adverse prognosis

This study aimed to determine the incidence/prognostic impact of TP53 mutation in 318 myelodysplastic syndrome (MDS) patients, and to correlate the changes to cytogenetics, single nucleotide polymorphism array karyotyping and clinical outcome. The median age was 65 years (17–89 years) and median follow‐up was 45 months [95% confidence interval (CI) 27–62 months]. TP53 mutations occurred in 30 (9·4%) patients, exclusively in isolated del5q (19%) and complex karyotype (CK) with ‐5/5q‐(72%), correlated with International Prognostic Scoring System intermediate‐2/high, TP53 protein expression, higher blast count and leukaemic progression. Patients with mutant TP53 had a paucity of mutations in other genes implicated in myeloid malignancies. Median overall survival of patients with TP53 mutation was shorter than wild‐type (9 versus 66 months, P < 0·001) and it retained significance in multivariable model (Hazard Ratio 3·8, 95%CI 2·3–6·3,P < 0·001). None of the sequentially analysed samples showed a disappearance of the mutant clone or emergence of new clones, suggesting an early occurrence of TP53 mutations. A reduction in mutant clone correlated with response to 5‐azacitidine, however clones increased in non‐responders and persisted at relapse. The adverse impact of TP53 persists after adjustment for cytogenetic risk and is of practical importance in evaluating prognosis. The relatively common occurrence of these mutations in two different prognostic spectrums of MDS, i.e. isolated 5q‐ and CK with ‐5/5q‐, possibly implies two different mechanistic roles for TP53 protein.     

Relative expression analysis of IL‐5 and IL‐6 genes in tropical sheep breed Pelibuey infected with Haemonchus contortus

Haemonchus contortus is a parasitic nematode of Pelibuey sheep, a meat breed used in tropical regions. Due to anthelmintic problems, the identification of hosts resistant to H. contortus is another option of control. The aim of this study was to analyse the relative expression of IL‐5 and IL‐6 genes in Pelibuey sheep after H. contortus infection. Nineteen lambs infected with H. contortus and three more lambs without infection were studied. The haemonchosis was determined by the number of eggs per gram of faeces (epg) and by the estimation of the percentage of the packed cell volume (%pcv). Peripheral blood mononuclear cells (PBMCs) were obtained to extract RNA at 0, 1, 2, 7, 14, 21 and 28 days after infection to quantify the relative expression of IL‐5, IL‐6 and GAPDH by real‐time PCR. Five lambs were classified as low responders (lr) to haemonchosis with averages of 1519 ± 315·3 epg and 31·49 ± 5·13%pcv, and 14 lambs were identified as high responders (hr) with averages of 530 ± 132 epg and 34·88 ± 3·75%pcv. The expression ratio of IL‐5 was significantly different compared with control lambs at 2, 7 and 14 days post‐infection (PI), and IL‐6 was significantly different after 14 days. The highest level of relative expression for IL‐5 and IL‐6 genes was 9·9‐fold and 12‐fold after 2 and 14 days for hr hosts (P < 0·05) compared with control group, respectively. In conclusion, the Pelibuey breed in grazing areas exhibited different expression of IL‐5 and IL‐6 obtained from PBMCs against H. contortus, suggesting the importance of these cytokines in regulating the nematode infection.     

FGF23 Level and Intima‐Media Thickness Are Elevated From Early Stages of Chronic Kidney Disease

Considering high cardiovascular (CV) risk in chronic kidney disease (CKD), the aim of this cross‐sectional study was to assess the association between carotid intima‐media thickness (IMT) and fibroblast growth factor (FGF) 23 as important players in CV pathophysiology. Eighty‐seven patients with mean estimated glomerular filtration rate 40.1 mL/min per 1.73 m² were involved. FGF23 and IMT were elevated from early stages of CKD. Mean IMT value was 1.10 ± 0.20 mm, being significantly elevated starting from early CKD, showing no correlation with FGF23 (r = ?0.01, P = ?0.91). Unlike the FGF23 level that followed worsening of kidney function, IMT was increasing only in the initial CKD stages, with no further increase from CKD stage 3 on. Although we found no direct association between current use of vitamin D and statin therapy, this may be associated with the sustained reference values of lipid and vitamin D status under treatment that further preclude worsening of IMT in patients with advanced CKD.     

The development of hypophosphataemic osteomalacia with myopathy in two patients with HIV infection receiving tenofovir therapy

We report two cases in which osteomalacia developed in patients on tenofovir-containing highly active antiretroviral therapy (HAART) in the context of Fanconi syndrome with hypophosphataemia. Bone pain was the presenting feature and myopathy followed in one case. Disability was reversed with withdrawal of the drug and with mineral supplementation. The cases highlight the importance of considering the diagnosis of osteomalacia in patients treated with tenofovir. A possible association with incipient acute renal failure, particularly during nonsteroidal anti-inflammatory drug (NSAID) use, needs further investigation.     

McCune-Albright综合征合并低血磷性佝偻病4例并文献复习

目的：总结4例McCune-Albright综合征合并低血磷性佝偻病患者的临床资料,以提高临床医师对该病的认识。方法回顾性分析北京协和医院确诊的4例McCune-Albright综合征合并低血磷性佝偻病患者的临床表现、实验室检查、影像学特点、治疗及转归,并进行文献复习。结果临床特点：4例McCune-Albright综合征合并低血磷性佝偻病患者均为女性,10岁前起病,均为多骨型骨纤维异样增殖症,主要临床表现为骨痛、骨骼畸形和脆性骨折。其中2例合并甲状腺功能亢进,2例合并周围性性早熟。实验室检查：4例患者均显示低磷血症（0.53～1.03mmol/L）和高碱性磷酸酶水平（464～1930U/L）,3例患者血β-1型胶原交联羧基末端肽（β-CTX）水平升高,2例患者血全长成纤维细胞生长因子23（intactFGF23）水平升高。影像学特点：4例患者影像学检查结果均符合骨纤维异常增殖症。其中3例患者有典型的佝偻病表现。4例患者均接受全身骨扫描显像,3例患者全身骨骼多发放射性浓聚区。治疗及转归：经给予活性维生素D、中性磷合剂和双膦酸盐,患者的临床症状和生化异常均显著改善。复习文献发现,患者起病越早,骨骼病变相对越重、血磷越低、骨转换指标升高越明显、血FGF23水平越高。结论McCune-Albright综合征合并低血磷性佝偻病是罕见病。对McCune-Albright综合征患者需注意筛查是否合并低血磷性佝偻病,以避免漏诊,改善预后。     

Role of IFN‐λs,IFN‐λs related genes and the DEPDC5 gene in Hepatitis B virus‐related liver disease

Recent studies have associated genetic variation near the interleukin 28B (IL28B/IFN‐λ3) gene with natural clearance of the hepatitis C virus (HCV) infection, and a common variant in the DEP domain containing 5 (DEPDC5) locus on chromosome 22 has been shown to affect susceptibility to hepatocellular carcinoma (HCC) in Japanese individuals with chronic HCV infection. This study was conducted to determine whether polymorphisms near or in interferon‐lambda (IFN‐λs) genes and their receptor genes such as interleukin 28 receptor, alpha (IL28RA) and interleukin 10 receptor, beta (IL10RB) as well as p21_activated kinases 4 (PAK4) and iron/zinc purple acid phosphatase‐like protein (PAPL), which are locate upstream of IFN‐λs, and lastly the DEPDC5 gene are associated with hepatitis B virus‐related liver disease in Han Chinese. The study subjects included 507 normal healthy controls, 350 individuals with natural clearance of HBV and 792 HBV‐infected patients. The patients were categorized into 157 inactive carriers (Case I), 216 active carriers (Case II), 111 cirrhotics (Case III) and 308 HCC patients (Case IV) subgroups. Seven single nucleotide polymorphisms (SNPs) were genotyped using the Matrix‐assisted Laser Desorption/Ionisation mass spectrometric (MALDI‐TOF MS) SNP genotyping assay. Rs423058 upstream of PAPL, rs2834167 in IL10RB and rs1012068 in DEPDC5 were associated with chronic HBV status, HBV natural clearance and the presence of HCC (P = 0.0004–0.024), respectively. PAPL, IL10RB and DEPDC5 polymorphisms have an impact on progression of HBV‐related liver disease. However, IFN‐λs genes as a tool to differentiate between different clinical courses of HBV infection were not useful in the Han Chinese population.