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The group of sclerosing bone dysplasia's is a clinically and genetically heterogeneous group of rare bone disorders which, according to the latest Nosology and classification of genetic skeletal disorders (2015), can be subdivided in three subgroups; the neonatal osteosclerotic dysplasias, the osteopetroses and related disorders and the other sclerosing bone disorders. Here, we give an overview of the most important radiographic and clinical symptoms, the underlying genetic defect and potential treatment options of the different sclerosing dysplasias included in these subgroups., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This chapter deals with a few of the important childhood bone disorders associated with high bone mass as well as conditions associated with fragility fractures and limb deformities that have not been addressed in previous chapters. A couple of skeletal dysplasias that can sometimes be confused with rickets are also dealt with in this chapter., (© 2015 S. Karger AG, Basel.)

Unlabelled: To achieve an efficient molecular diagnosis of osteogenesis imperfecta (OI), Ehlers-Danlos syndrome (EDS), and osteopetrosis (OPT), we designed a next-generation sequencing (NGS) platform to sequence 34 genes. We validated this platform on known cases and have successfully identified the causative mutation in most patients without a prior molecular diagnosis., Introduction: Osteogenesis imperfecta, Ehlers-Danlos syndrome, and osteopetrosis are collectively common inherited skeletal diseases. Evaluation of subjects with these conditions often includes molecular testing which has important counseling and therapeutic and sometimes legal implications. Since several different genes have been implicated in these conditions, Sanger sequencing of each gene can be a prohibitively expensive and time-consuming way to reach a molecular diagnosis., Methods: In order to circumvent these problems, we have designed and tested a NGS platform that would allow simultaneous sequencing on a single diagnostic platform of different genes implicated in OI, OPT, EDS, and other inherited conditions, leading to low or high bone mineral density. We used a liquid-phase probe library that captures 602 exons (~100 kb) of 34 selected genes and have applied it to test clinical samples from patients with bone disorders., Results: NGS of the captured exons by Illumina HiSeq 2000 resulted in an average coverage of over 900X. The platform was successfully validated by identifying mutations in six patients with known mutations. Moreover, in four patients with OI or OPT without a prior molecular diagnosis, the assay was able to detect the causative mutations., Conclusions: In conclusion, our NGS panel provides a fast and accurate method to arrive at a molecular diagnosis in most patients with inherited high or low bone mineral density disorders.

Bone mineral density (BMD) is a quantitative trait for which the heritability of the variance is estimated to be up to 80%, based on epidemiological and twin studies. Further illustration of the involvement of genetic factors in bone homeostasis, is the existence of an extended group of genetic conditions associated with an abnormal bone density. The group of conditions with increased bone density has long been poorly studied and understood at the molecular genetic level but recently, thanks to recent developments in molecular genetics and genomics, for some of them major breakthroughs have been made. These findings will make the molecular analysis of such patients an additional tool in diagnostics and in genetic counseling. However, the initial identification of affected patients is still largely dependent upon recognition of clinical and radiological stigmata of the disease. Therefore, in this overview of sclerosing bone dysplasias, the classical clinical and radiological signs of this group of disorders will be discussed along with the new molecular insights.

Sclerosteosis is a unique autosomal recessive condition in which skeletal overgrowth is associated with syndactyly and digital malformation. Analysis of the course and clinical features in 25 affected individuals showed that the condition is progressive and potentially lethal. Facial palsy and deafness are common complications and raised intracranial pressure may develop. The clinical and radiographic stigmata of sclerosteosis permit differentiation from the other disorders of the "osteopetrosis" or "Albers-Schönberg disease" group, in which bony thickening and cranial nerve palsy occur.