Christine Burren

Risedronate in children with osteogenesis imperfecta: a randomised, double-blind, placebo-controlled trial

BACKGROUNDnChildren with osteogenesis imperfecta are often treated with intravenous bisphosphonates. We aimed to assess the safety and efficacy of risedronate, an orally administered third-generation bisphosphonate, in children with the disease.nnnMETHODSnIn this multicentre, randomised, parallel, double-blind, placebo-controlled trial, children aged 4-15 years with osteogenesis imperfecta and increased fracture risk were randomly assigned by telephone randomisation system in a 2:1 ratio to receive either daily risedronate (2·5 or 5 mg) or placebo for 1 year. Study treatment was masked from patients, investigators, and study centre personnel. Thereafter, all children received risedronate for 2 additional years in an open-label extension. The primary efficacy endpoint was percentage change in lumbar spine areal bone mineral density (BMD) at 1 year. The primary efficacy analysis was done by ANCOVA, with treatment, age group, and pooled centre as fixed effects, and baseline as covariate. Analyses were based on the intention-to-treat population, which included all patients who were randomly assigned and took at least one dose of assigned study treatment. The trial is registered with ClinicalTrials.gov, number NCT00106028.nnnFINDINGSnOf 147 patients, 97 were randomly assigned to the risedronate group and 50 to the placebo group. Three patients from the risedronate group and one from the placebo group did not receive study treatment, leaving 94 and 49 in the intention-to-treat population, respectively. The mean increase in lumbar spine areal BMD after 1 year was 16·3% in the risedronate group and 7·6% in the placebo group (difference 8·7%, 95% CI 5·7-11·7; p<0·0001). After 1 year, clinical fractures had occurred in 29 (31%) of 94 patients in the risedronate group and 24 (49%) of 49 patients in the placebo group (p=0·0446). During years 2 and 3 (open-label phase), clinical fractures were reported in 46 (53%) of 87 patients in the group that had received risedronate since the start of the study, and 32 (65%) of 49 patients in the group that had been given placebo during the first year. Adverse event profiles were otherwise similar between the two groups, including frequencies of reported upper-gastrointestinal and selected musculoskeletal adverse events.nnnINTERPRETATIONnOral risedronate increased areal BMD and reduced the risk of first and recurrent clinical fractures in children with osteogenesis imperfecta, and the drug was generally well tolerated. Risedronate should be regarded as a treatment option for children with osteogenesis imperfecta.nnnFUNDINGnAlliance for Better Bone Health (Warner Chilcott and Sanofi).

Germline or somatic GPR101 duplication leads to X-linked acrogigantism: a clinico-pathological and genetic study.

Non-syndromic pituitary gigantism can result from AIP mutations or the recently identified Xq26.3 microduplication causing X-linked acrogigantism (XLAG). Within Xq26.3, GPR101 is believed to be the causative gene, and the c.924Gu2009>u2009C (p.E308D) variant in this orphan G protein-coupled receptor has been suggested to play a role in the pathogenesis of acromegaly.We studied 153 patients (58 females and 95 males) with pituitary gigantism. AIP mutation-negative cases were screened for GPR101 duplication through copy number variation droplet digital PCR and high-density aCGH. The genetic, clinical and histopathological features of XLAG patients were studied in detail. 395 peripheral blood and 193 pituitary tumor DNA samples from acromegaly patients were tested for GPR101 variants.We identified 12 patients (10 females and 2 males; 7.8xa0%) with XLAG. In one subject, the duplicated region only contained GPR101, but not the other three genes found to be duplicated in the previously reported patients, defining a new smallest region of overlap of duplications. While females presented with germline mutations, the two male patients harbored the mutation in a mosaic state. Nine patients had pituitary adenomas, while three had hyperplasia. The comparison of the features of XLAG, AIP-positive and GPR101&AIP-negative patients revealed significant differences in sex distribution, age at onset, height, prolactin co-secretion and histological features. The pathological features of XLAG-related adenomas were remarkably similar. These tumors had a sinusoidal and lobular architecture. Sparsely and densely granulated somatotrophs were admixed with lactotrophs; follicle-like structures and calcifications were commonly observed. Patients with sporadic or familialxa0acromegaly did not have an increased prevalence of the c.924Gu2009>u2009C (p.E308D) GPR101 variant compared to public databases.In conclusion, XLAG can result from germline or somatic duplication of GPR101. Duplication of GPR101 alone is sufficient for the development of XLAG, implicating it as the causative gene within the Xq26.3 region. The pathological features of XLAG-associated pituitary adenomas are typical and, together with the clinical phenotype, should prompt genetic testing.

Middle-term use of Cinacalcet in paediatric dialysis patients

The effects of the calcimimetic drug Cinacalcet were assessed in six children with uncontrolled hyperparathyroidism secondary to stage 5 chronic kidney disease (CKD). Data were collected retrospectively regarding bone biochemistry and medications. Patients were between the ages of 11xa0months and 14xa0years on commencing Cinacalcet at initial doses of 0.4–1.4xa0mg/kg. Treatment, which was well tolerated in the majority and still on going in five patients, was for periods ranging between 3xa0months and 3xa0years. All six cases saw at least an 86% reduction in serum parathyroid hormone (PTH). Hypophosphataemia and/or hypocalcaemia were observed in three cases. Overall, achievement of UK Renal Association targets for corrected calcium (Ca), phosphate (P) and the calcium × phosphate product (Ca × P) were unaffected. We conclude that Cinacalcet is an effective treatment for correcting and sustaining correction of uncontrollable PTH levels seen in a difficult group of patients. Importantly, it has allowed the avoidance of parathyroidectomy for a significant time period in all cases. There remain questions about the effect of Cinacalcet on linear growth amongst paediatric dialysis patients, and future studies should aim to address this.

Inpatient care for children with diabetes: are standards being met?

Background Hospital inpatient care is frequently mentioned by parents as unsatisfactory for children with diabetes. Ward staff are now less familiar with diabetes, as admissions are less common and diabetes management is more intensive. Objective To compare current practice with Department of Health Childrens Diabetes Working Group care standards. Methods This audit surveyed the organisation of inpatient care for children with diabetes in three regional networks in southern England, and was funded by the Healthcare Quality Improvement Partnership. Results All 27 services completed the questionnaire. Protocols for diabetic ketoacidosis, surgery, new diagnosis and hypoglycaemia were generally available on wards (70% had all four protocols) but less available in emergency departments (EDs) (52%). Trained childrens nurses worked on every shift in childrens wards (100%) but not necessarily in EDs (33%). Diabetes link nurses were identified on 74% of wards and 61% of high-dependency units (HDUs), and diabetes specialist nurses have inpatient liaison in their job description (89%) and working role (93%). Standards achieved less often were access to dietetic advice on wards (37%), education sessions for ED and ward staff, and informing diabetes team (only 26% within 2 h of admission during the day, and only 11% would contact the diabetes consultant overnight for a child admitted to a paediatric intensive care unit/HDU). Half of centres reported insulin errors. Conclusions This first audit of childrens diabetes inpatient care organisation demonstrates that some standards can be achieved, but others, such as having childrens nurses on every shift in EDs, lack of dietetic advice to ward staff, and liaison with the diabetes team quickly out of hours, are more challenging. Further planned audit outcomes are to produce patient and parent literature for children admitted to hospital and to refine the standards further.

Attitudes to Exercise and Diabetes in Young People with Type 1 Diabetes Mellitus: A Qualitative Analysis

Aims To investigate young people’s attitudes to, and understanding of, physical activity on glycaemic control in Type 1 Diabetes Mellitus. Methods Four focus groups with 11–14 and 15–16 year olds were conducted with twelve young people with Type 1 Diabetes, from within a larger study investigating physical activity and fitness. Qualitative analysis of the focus group data was performed using Interpretative Phenomenological Analysis. Results Four superordinate themes were identified: Benefits of Exercise, Knowledge and Understanding, Information and Training and “You can do anything”. Young people felt that exercising helped them to manage their diabetes and had a beneficial psychological and physical impact on their bodies. They reported a lack of knowledge and understanding about diabetes among school staff and other young people. The overwhelming sense from young people was that although diabetes impacts upon their lives, with preparation, physical activity can take place as normal. Conclusions Whilst young people had an awareness of the physical and psychological benefits of exercise in managing their diabetes, they experienced difficulties at school. Professional support and discussions with young people, giving tailored strategies for managing Type 1 Diabetes during exercise are needed. Healthcare teams should ensure that the support and educational needs of school staff are met. Providing more opportunities to empower young people to take on the responsibility for their Type 1 Diabetes care is merited. Young people felt diabetes did not stop them from participating in activities; it is simply a part of them that needs managing throughout life.

Diagnostic and management challenges from childhood, puberty through to transition in severe insulin resistance due to insulin receptor mutations

Two Caucasian girls, both of normal weight and body mass indices, were diagnosed with type A insulin resistance (IR) in childhood. Case 1 presented with premature adrenarche aged 7 years, then by age 12 years had hirsutism, acne, acanthosis nigricans, and asymptomatic diabetes. Subsequent investigation revealed raised adiponectin (15.3u2009mg/L) and heterozygous p.Pro1205Leu mutation in the INSR gene encoding the insulin receptor. She experienced postprandial hypoglycaemia on metformin; acarbose was trialled and discontinued aged 16 years, as she became normoglycaemic. Hirsutism was treated with topical eflornithine, oral spironolactone and flutamide, and laser therapy. Unfortunately, diabetes reemerged in young adulthood with obesity. Case 2: during an emergency admission for acute abdominal pain aged 11 years, hyperglycaemia was noted which led to further investigation. An oral glucose tolerance test showed diabetes and ultrasound showed polycystic ovaries. Further investigations revealed raised adiponectin (18u2009mg/L) and compound heterozygous mutations in the INSR gene: p.Pro1263Ala and p.Ser748Leu (latter probable normal variant). She was treated with metformin and experienced postprandial hypoglycaemia. Symptoms of hyperandrogenism were controlled by flutamide. She maintained a healthy weight and reassessment at young adulthood showed resolution of diabetes. Type A IR may present in childhood with overlapping features of common endocrine entities such as premature adrenarche and polycystic ovarian syndrome. Patients with abnormal glucose tolerance yet normal weight merit screening with adiponectin; raised adiponectin levels prompt insulin receptor mutational analysis. Postprandial hypoglycaemia is characteristic. Management includes optimization of glycaemic control with oral hypoglycaemic agents and maintenance of healthy weight, and controlling the effects of hyperandrogenism.

Improving patient outcomes in fibrous dysplasia/McCune-Albright syndrome: an international multidisciplinary workshop to inform an international partnership

SummaryTo develop consensus on improving the management of patients, we convened an international workshop involving patients, clinicians, and researchers. Key findings included the diagnostic delay and variability in subsequent management with agreement to develop an international natural history study. We now invite other stakeholders to join the partnership.PurposeThe aim of this study was develop a consensus on how to improve the management of patients with fibrous dysplasia and prioritize areas for researchMethodsAn international workshop was held over 3xa0days involving patients, clinicians, and researchers. Each day had a combination of formal presentations and facilitated discussions that focused on clinical pathways and research.ResultsThe patient workshop day highlighted the variability of patients’ experience in getting a diagnosis, the knowledge of general clinical staff, and understanding long-term outcomes. The research workshop prioritized collaborations that improved understanding of the contemporary natural history of fibrous dysplasia/McCune-Albright syndrome (FD/MAS). The clinical workshop outlined the key issues around diagnostics, assessment of severity, treatment and monitoring of patients.ConclusionsIn spite of advances in understanding the genetic and molecular underpinnings of fibrous dysplasia/McCune-Albright syndrome, clinical management remains a challenge. From the workshop, a consensus was reached to create an international, multi-stakeholder partnership to advance research and clinical care in FD/MAS. We invite other stakeholders to join the partnership.

Hartsfield syndrome associated with a novel heterozygous missense mutation in FGFR1 and incorporating tumoral calcinosis

Hartsfield Syndrome Associated with a Novel Heterozygous Missense Mutation in FGFR1 and Incorporating Tumoral Calcinosis Rathi Prasad, Carole Brewer, and Christine P. Burren* Department of Paediatric Endocrinology, Bristol Royal Hospital for Children, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom Department of Clinical Genetics, Royal Devon & Exeter Hospital, Exeter, United Kingdom

TRPV6 compound heterozygous variants result in impaired placental calcium transport and severe undermineralization and dysplasia of the fetal skeleton

Transient receptor potential vanilloid 6 (TRPV6) functions in tetramer form for calcium transport. Until now, TRPV6 has not been linked with skeletal development disorders. An infant with antenatal onset thoracic insufficiency required significant ventilatory support. Skeletal survey showed generalized marked undermineralization, hypoplastic fractured ribs, metaphyseal fractures, and extensive periosteal reaction along femoral, tibial, and humeral diaphyses. Parathyroid hormone (PTH) elevation (53.4–101u2009pmol/L) initially suggested PTH signaling disorders. Progressively, biochemical normalization with radiological mineralization suggested recovery from in utero pathophysiology. Genomic testing was undertaken and in silico protein modeling of variants. No abnormalities in antenatal CGH array or UPD14 testing. Postnatal molecular genetic analysis found no causative variants in CASR, GNA11, APS21, or a 336 gene skeletal dysplasia panel investigated by whole exome sequencing. Trio exome analysis identified compound heterozygous TRPV6 likely pathogenic variants: novel maternally inherited missense variant, c.1978Gu2009>u2009C p.(Gly660Arg), and paternally inherited nonsense variant, c.1528Cu2009>u2009T p.(Arg510Ter), confirming recessive inheritance. p.(Gly660Arg) generates a large side chain protruding from the C‐terminal hook into the interface with the adjacent TRPV6 subunit. In silico protein modeling suggests steric clashes between interface residues, decreased C‐terminal hook, and TRPV6 tetramer stability. The p.(Gly660Arg) variant is predicted to result in profound loss of TRPV6 activity. This first case of a novel dysplasia features severe but improving perinatal abnormalities. The TRPV6 compound heterozygous variants appear likely to interfere with fetoplacental calcium transfer crucial for in utero skeletal development. Astute clinical interpretation of evolving perinatal abnormalities remains valuable in complex calcium and bone pathophysiology and informs exome sequencing interpretation.

Pamidronate “zebra lines”: A treatment timeline

Osteogenesis imperfecta is a hereditary bone dysplasia characterized by bone fragility, deformity, and short stature. Treatment focuses on preventing bone fractures and symptom relief. Pamidronate, a second-generation bisphosphonate drug that minimizes bone loss, is the chosen treatment in osteogenesis imperfecta. Radiologically, each cycle of pamidronate treatment is depicted as a line of sclerosed nondecalcified cartilage at the metaphysis, termed a pamidronate line. In this case report, we demonstrate that a treatment timeline can be visualized on plain radiographs as the number and spacing of pamidronate lines reflects the number and timing of treatment cycles. The educational value of this is to reassure physicians of the benign nature of “zebra lines,” to demonstrate that the pamidronate lines migrate and fade with bone growth, and alert physicians that the lack of expected pamidronate lines during treatment may reflect a change in the patients condition that reduces the effectiveness of bisphosphonate infusions.