Next-generation sequencing of common osteogenesis imperfecta-related genes in clinical practice

Next generation sequencing (NGS) is a rapidly developing area in genetics. Utilizing this technology in the management of disorders with complex genetic background and not recurrent mutation hot spots can be extremely useful. In this study, we applied NGS, namely semiconductor sequencing to determine the most significant osteogenesis imperfecta-related genetic variants in the clinical practice. We selected genes coding collagen type I alpha-1 and-2 (COL1A1, COL1A2) which are responsible for more than 90% of all cases. CRTAP and LEPRE1/P3H1 genes involved in the background of the recessive forms with relatively high frequency (type VII and VIII) represent less than 10% of the disease. In our six patients (1-41 years), we identified 23 different variants. We found a total of 14 single nucleotide variants (SNV) in COL1A1 and COL1A2, 5 in CRTAP and 4 in LEPRE1. Two novel and two already well-established pathogenic SNVs have been identified. Among the newly recognized mutations, one results in an amino acid change and one of them is a stop codon. We have shown that a new full-scale cost-effective NGS method can be developed and utilized to supplement diagnostic process of osteogenesis imperfecta with molecular genetic data in clinical practice

The boy who refused an IV: a case report of subcutaneous clodronate for bone pain in a child with Ewing Sarcoma

BACKGROUND: Bone pain in malignancy can be challenging to treat. Bisphosphonates have been found to be useful in adults with bone pain, but there are no reports of their use in children for this indication. In pediatric palliative medicine there are hurdles in translating knowledge gained primarily in adult studies into application in children. Obstacles exist in initially determining whether the evidence supports using a drug in children, and once a drug is chosen, then determining the optimal route of delivery. There is very little data to guide pediatric practitioners in this situation. CASE PRESENTATION: A 9 year old boy with disseminated Ewing Sarcoma presented with extremity pain not responsive to a combination of opiates, gabapentin and non-steroidal anti-inflammatory drugs. Clodronate, a bisphosphonate, was added to the regimen to treat bone pain. It was given subcutaneously every 4 weeks with a good response and no side effects. CONCLUSION: This case report describes the use of a bisphosphonate, clodronate, given subcutaneously to a child with Ewing sarcoma with effective relief of bone pain. It describes how the care team encountered the challenges inherent in translating adult therapy into a pediatric regimen. Furthermore the report details how a regimen was developed to address this child's concerns regarding medication administration. Further effort needs to be made at finding solutions to address the lack of good evidence for pediatric palliative therapies

Genetic evaluation of suspected osteogenesis imperfecta (OI)

Osteogenesis imperfecta (OI) is probably the most common genetic form of fracture predisposition. The term OI encompasses a broad range of clinical presentations that may be first apparent from early in pregnancies to late in life, reflecting the extent of bone deformity and fracture predisposition at different stages of development or postnatal ages. Depending on the age of presentation, OI can be difficult to distinguish from some other genetic and nongenetic causes of fractures, including nonaccidental injury (abuse). The strategies for evaluation and the testing discussed here provide guidelines for evaluation that should help to distinguish among causes for fracture and bone deformity

Growth characteristics in individuals with osteogenesis imperfecta in North America: results from a multicenter study.

PurposeOsteogenesis imperfecta (OI) predisposes people to recurrent fractures, bone deformities, and short stature. There is a lack of large-scale systematic studies that have investigated growth parameters in OI.MethodsUsing data from the Linked Clinical Research Centers, we compared height, growth velocity, weight, and body mass index (BMI) in 552 individuals with OI. Height, weight, and BMI were plotted on Centers for Disease Control and Prevention normative curves.ResultsIn children, the median z-scores for height in OI types I, III, and IV were -0.66, -6.91, and -2.79, respectively. Growth velocity was diminished in OI types III and IV. The median z-score for weight in children with OI type III was -4.55. The median z-scores for BMI in children with OI types I, III, and IV were 0.10, 0.91, and 0.67, respectively. Generalized linear model analyses demonstrated that the height z-score was positively correlated with the severity of the OI subtype (P < 0.001), age, bisphosphonate use, and rodding (P < 0.05).ConclusionFrom the largest cohort of individuals with OI, we provide median values for height, weight, and BMI z-scores that can aid the evaluation of overall growth in the clinic setting. This study is an important first step in the generation of OI-specific growth curves

Estimating bone mass in children: can bone health index replace dual energy x-ray absorptiometry?

BACKGROUND: Bisphosphonates have been shown to increase metacarpal cortical width. Bone health index is computed from hand radiographs by measuring cortical thickness, width and length of the three middle metacarpals, and may potentially help predict fracture risk in children. OBJECTIVE: To compare bone health index with bone mineral density as measured from dual energy X-ray absorptiometry scans in patients with and without bisphosphonate treatment. MATERIALS AND METHODS: Two hundred ninety-three Caucasian patients (mean age: 11.5±3.7 years) were included. We documented absolute values and z-scores for whole-body less head and lumbar spine bone mineral density then correlated these with the bone health index, which were acquired on the same day, in different patient groups, depending on their ethnicity and diagnosis. RESULTS: Bone health index showed moderate to strong correlation with absolute values for whole-body (r=0.52) and lumbar spine (r=0.70) bone mineral density in those not treated with bisphosphonates and moderate correlation absolute values for whole-body (r=0.54) and lumber spine (r=0.51) bone mineral density for those treated with bisphosphonates. There was weak correlation of z-scores, ranging from r=0.11 to r=0.35 in both groups. CONCLUSION: The lack of a strong correlation between dual energy X-ray absorptiometry and bone health index suggests that they may be assessing different parameters

EMQN best practice guidelines for the laboratory diagnosis of osteogenesis imperfecta

Osteogenesis imperfecta (OI) comprises a group of inherited disorders characterized by bone fragility and increased susceptibility to fractures. Historically, the laboratory confirmation of the diagnosis OI rested on cultured dermal fibroblasts to identify decreased or abnormal production of abnormal type I (pro)collagen molecules, measured by gel electrophoresis. With the discovery of COL1A1 and COL1A2 gene variants as a cause of OI, sequence analysis of these genes was added to the diagnostic process. Nowadays, OI is known to be genetically heterogeneous. About 90% of individuals with OI are heterozygous for causative variants in the COL1A1 and COL1A2 genes. The majority of remaining affected individuals have recessively inherited forms of OI with the causative variants in the more recently discovered genes CRTAP, FKBP10, LEPRE1,PLOD2, PPIB, SERPINF1, SERPINH1 and SP7, or in other yet undiscovered genes. These advances in the molecular genetic diagnosis of OI prompted us to develop new guidelines for molecular testing and reporting of results in which we take into account that testing is also used to ‘exclude' OI when there is suspicion of non-accidental injury. Diagnostic flow, methods and reporting scenarios were discussed during an international workshop with 17 clinicians and scientists from 11 countries and converged in these best practice guidelines for the laboratory diagnosis of OI

Syndromes with congenital brittle bones

BACKGROUND: There is no clear definition of osteogenesis imperfecta (OI). The most widely used classification of OI divides the disease in four types, although it has been suggested that there may be at least 12 forms of OI. These forms have been named with numbers, eponyms or descriptive names. Some of these syndromes can actually be considered congenital forms of brittle bones resembling OI (SROI). DISCUSSION: A review of different syndromes with congenital brittle bones published in the literature is presented. Syndromes are classified in "OI" (those secondary to mutations in the type I pro-collagen genes), and "syndromes resembling OI" (those secondary to mutations other that the type I pro-collagen genes, identified or not). A definition for OI is proposed as a syndrome of congenital brittle bones secondary to mutations in the genes codifying for pro-collagen genes (COL1A1 and COL1A2). SUMMARY: A debate about the definition of OI and a possible clinical and prognostic classification are warranted