117 Chapter 6 Introduction Although Osteogenesis Imperfecta (OI) is commonly defined as ‘brittle bones’ disease, it has more characteristics, like blue sclerae, hearing loss, dental problems, ligamentous laxity and short stature. OI is to the result of a hereditary defect in collagen type I synthesis. Nowadays, there are various classifications, with that of van Dijk et al. being most commonly used 1. The prevalence of OI is estimated at about 6.5 per 100,000 live births 2. Easy bruising and bleeding are prominent features of some heritable disorders of the connective tissue and are most prominent in Ehlers-Danlos syndrome (EDS). Heritable disorders of the connective tissue can be a result of fragility of capillaries and the perivascular connective tissue, but also of clotting or platelet dysfunction 3. It can also be associated with a disorder of vascular haemostasis or a defect in fibrinolysis 4. Although EDS is clearly associated with bleeding disorders 5, the literature for OI in relation to bleeding disorders and their underlying mechanism is sparse and often outdated 6–9. The first study of OI with an association to bleeding disorders dates back to 1957 and was done by Siegel et al. 6. Even more than 60 years later, reference is still being made to these initial articles due to limited new research. In 2018, the Isala Expertise Centre for adults with OI in Zwolle the Netherlands, conducted research into bleeding diathesis among OI patients for the first time since 1984, using a validated self-administered bleeding questionnaire (self-BAT) and modern laboratory techniques in 22 OI patients 10. After this pilot study, self-BAT questionnaires were distributed among a large cohort of 328 OI patients, resulting in 195 available bleeding scores 11. In this paper we report on extensive laboratory testing among 11 OI patients from this cohort with the highest bleeding scores versus a random sample of 9 OI patients with low (normal) scores on the self-BAT. The aim of this study was to identify or exclude coagulation disorders in OI patients with the highest bleeding tendencies based on the self-BAT questionnaire in comparison to OI patients within the normal bleeding score range. This study provides data on laboratory results in relation to bleeding tendency in a small group of adult OI patients. However, considering the precise selection process of the data, it might be extrapolated to the presence or absence of coagulation disorders in the whole OI population. This may lead to clinical guidelines regarding the increased bleeding tendency in OI, which is highly desirable.
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