Tim Cundy

LDL Receptor-Related Protein 5 (LRP5) Affects Bone Accrual and Eye Development

In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.

Perinatal mortality in Type 2 diabetes mellitus

Aims In many parts of the world the number of pregnancies in women with Type 2 diabetes mellitus (DM) now exceeds that in women with Type 1 DM, but there are few data published on perinatal mortality in Type 2 DM. This study reports observational data on perinatal mortality in Type 2 DM from a population with a high background rate of this disorder.

Severe hypomagnesaemia in long-term users of proton-pump inhibitors

Objective  To explore the mechanism underlying severe hypomagnesaemia in long‐term users of proton‐pump inhibitors (PPIs).

Camurati-Engelmann disease: review of the clinical, radiological, and molecular data of 24 families and implications for diagnosis and treatment

Camurati-Engelmann disease (CED) is a rare autosomal dominant type of bone dysplasia. This review is based on the unpublished and detailed clinical, radiological, and molecular findings in 14 CED families, comprising 41 patients, combined with data from 10 other previously reported CED families. For all 100 cases, molecular evidence for CED was available, as a mutation was detected in TGFB1, the gene encoding transforming growth factor (TGF) β1. Pain in the extremities was the most common clinical symptom, present in 68% of the patients. A waddling gait (48%), easy fatigability (44%), and muscle weakness (39%) were other important features. Radiological symptoms were not fully penetrant, with 94% of the patients showing the typical long bone involvement. A large percentage of the patients also showed involvement of the skull (54%) and pelvis (63%). The review provides an overview of possible treatments, diagnostic guidelines, and considerations for prenatal testing. The detailed description of such a large set of CED patients will be of value in establishing the correct diagnosis, genetic counselling, and treatment.

Congenital anomalies in the offspring of women with type 1, type 2 and gestational diabetes.

Aim To determine the frequency of major congenital anomalies in the offspring of women with gestational diabetes (GDM), classified according to their postpartum glucose tolerance status.

Biochemical and radiologic improvement in Paget's disease of bone treated with alendronate: A randomized, placebo-controlled trial

PURPOSE The potent bisphosphonates offer great promise in the management of Pagets disease of bone, but are currently available only as parenteral preparations in most countries. There is a need for a well-tolerated, oral therapy. Furthermore, none of the currently available therapies have been rigorously demonstrated to heal the lytic bone lesions characteristic of this condition. Alendronate is a potent new oral aminobisphosphonate that has shown promising effects on Pagets disease in preliminary studies. METHODS We report a double-blind, randomized comparison of oral alendronate 40 mg/day and placebo over 6 months in 55 patients with Pagets disease. Efficacy was determined from measurements of biochemical indices of bone turnover (serum alkaline phosphatase and urine N-telopeptide) and blinded radiologic assessment of lytic bone lesions. RESULTS N-telopeptide excretion declined by 86% and serum alkaline phosphatase by 73% in patients receiving alendronate, but remained stable in patients receiving placebo (P < 0.001 between groups for both indices). Responses were similar whether or not patients had previously received bisphosphonate treatment. Alendronate treatment normalized alkaline phosphatase in 48% of patients. Forty-eight percent of alendronate-treated patients showed radiologic improvement in osteolysis whereas in the placebo group only 4% improved (P = 0.02 for between-groups comparison). No patient in either group showed worsening of osteolysis. Bone histomorphometry indicated that alendronate tended to normalize turnover indices. There was no evidence of abnormal mineralization in bone biopsies taken from 12 alendronate-treated subjects. The treatment was well tolerated. CONCLUSION Oral alendronate appears to be a safe and effective therapy for Pagets disease and results in healing of lytic bone lesions.

Novel UBA Domain Mutations of SQSTM1 in Paget's Disease of Bone: Genotype Phenotype Correlation, Functional Analysis, and Structural Consequences

Three novel missense mutations of SQSTM1 were identified in familial PDB, all affecting the UBA domain. Functional and structural analysis showed that disease severity was related to the type of mutation but was unrelated to the polyubiquitin‐binding properties of the mutant UBA domain peptides.

Enhanced RANK ligand expression and responsivity of bone marrow cells in Paget’s disease of bone

Pagets disease is characterized by highly localized areas of increased osteoclast (OCL) activity. This suggests that the microenvironment in pagetic lesions is highly osteoclastogenic, or that OCL precursors in these lesions are hyperresponsive to osteoclastogenic factors (or both). To examine these possibilities, we compared RANK ligand (RANKL) mRNA expression in a marrow stromal cell line developed from a pagetic lesion (PSV10) with that in a normal stromal cell line (Saka), and expression in marrow samples from affected bones of Pagets patients with that in normal marrow. RANKL mRNA was increased in PSV10 cells and pagetic marrow compared with Saka cells and normal marrow, and was also increased in marrow from affected bones compared with uninvolved bones from Pagets patients. Furthermore, pagetic marrow cells formed OCLs at much lower RANKL concentrations than did normal marrow. Anti-IL-6 decreased the RANKL responsivity of pagetic marrow to normal levels, whereas addition of IL-6 to normal marrow enhanced RANKL responsivity. Thus, RANKL expression and responsivity is increased in pagetic lesions, in part mediated by IL-6. These data suggest that the combination of enhanced expression of RANKL in affected bones and increased RANKL sensitivity of pagetic OCL precursors may contribute to the elevated numbers of OCLs in Pagets disease.

Recovery of bone density in women who stop using medroxyprogesterone acetate

In order to determine whether the loss in bone density seen in users of depot medroxyprogesterone acetate is reversible, a comparative study was undertaken in three groups of women. Group 1 consisted of 14 women who had used the contraceptive for at least 3 years and then discontinued use. Group 2 was 22 longterm users, and Group 3 contained 18 women who had never used the drug and served as controls. Estrogen production resumed in all of the Group 1 women after discontinuation. Two bone density measurements were taken twice in each woman. At first measurement, lumbar spine density was an average of 9% lower in Groups 1 and 2 than in controls. At the second measurement, however, lumbar spine density had significantly increased in Group 1 while it remained the same for the other groups. No significant changes in femoral neck density were observed. Additional measurements in 8 women from Group 1 taken 2 years after discontinuation revealed a further significant increase in lumbar spine bone density. Thus, it was concluded that bone density loss is reversible, even in cases where women experience a significant weight loss after discontinuation.

Genomewide Search in Familial Paget Disease of Bone Shows Evidence of Genetic Heterogeneity with Candidate Loci on Chromosomes 2q36, 10p13, and 5q35

Paget disease of bone (PDB) is a common disorder characterized by focal abnormalities of increased and disorganized bone turnover. Genetic factors are important in the pathogenesis of PDB, and previous studies have shown that the PDB-like bone dysplasia familial expansile osteolysis is caused by activating mutations in the TNFRSF11A gene that encodes receptor activator of nuclear factor kappa B (RANK); however, linkage studies, coupled with mutation screening, have excluded involvement of RANK in the vast majority of patients with PDB. To identify other candidate loci for PDB, we conducted a genomewide search in 319 individuals, from 62 kindreds with familial PDB, who were predominantly of British descent. The pattern of inheritance in the study group as a whole was consistent with autosomal dominant transmission of the disease. Parametric multipoint linkage analysis, under a model of heterogeneity, identified three chromosomal regions with LOD scores above the threshold for suggestive linkage. These were on chromosomes 2q36 (LOD score 2.7 at 218.24 cM), 5q35 (LOD score 3.0 at 189.63 cM), and 10p13 (LOD score 2.6 at 41.43 cM). For each of these loci, formal heterogeneity testing with HOMOG supported a model of linkage with heterogeneity, as opposed to no linkage or linkage with homogeneity. Two-point linkage analysis with a series of markers from the 5q35 region in another large kindred with autosomal dominant familial PDB also supported linkage to the candidate region with a maximum LOD score of 3.47 at D5S2034 (187.8 cM). These data indicate the presence of several susceptibility loci for PDB and identify a strong candidate locus for the disease, on chromosome 5q35.