Introduction: Von Willebrand Disease (VWD) is the second most common inherited bleeding disorder. There is paucity of the literature describing the prevalence and clinical characteristics of VWD in this part of the world. The aim of the current study is to detect the prevalence, describe the spectrum of the different types of VWD, their mode of presentation, bleeding phenotype and outcome in Oman. Methods: A retrospective cross-sectional study was carried out in the 2 available referral tertiary care facilities in Oman namely; Sultan Qaboos University and the Royal Hospitals. The study included all children and adults diagnosed with VWD in Oman until June 2019. The patients were subtyped as per the International Society of Thrombosis and Haemostasis (ISTH) criteria. Data was collected from the electronic hospital systems in both hospitals. Out of 700 entries of VWD in both hospitals, only 140 were true cases and 560 were tested negative but wrongly labelled. Patients or their next of ken were called and interviewed to obtain the necessary information that was not documented in the electronic system. Results: A total of 140 patients are confirmed to have VWD giving a prevalence of 1:20000. Fifty eight patients are males (41.5%), 82 patients are females (58.5%). Sixty six patients have type I (47%), 38 patients have type II (27%) and 36 patients have type III (26%). The majority of patients 90 (64%) were diagnosed before the age of 20 years and 62 of them (68%) had positive family history of the disease. The most common presentation was recurrent unexplained bruising. As expected, patients with type III tend to have a significant bleeding phenotype with a bleeding score more than 5 in adults and 3 for paediatric patients. All of them were admitted to hospital at some point electively (for surgery) or for bleeding control, however, they were not put on prophylaxis. None of the patients had serious or intra-cranial bleeding. Conclusion: Von Willebrand Disease is not uncommon in Oman with an overall prevalence of 1:20000, however, it is much less than what was originally reported in previous studies in developing countries and the WFH website. The majority of patients are type 1 and have a positive family history of the disease. The disease is more common in females. All patients with type III have abnormal bleeding score and required VW factor replacement at one point. None of the patients had a serious bleed and they are not on prophylaxis. Keywords: Von Willebrand disease, Prevalence, Oman. Disclosures Al-Khabori: AstraZeneca: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; SOBI: Honoraria; NovoNardisk: Membership on an entity's Board of Directors or advisory committees; Shire (Takeda): Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees.

Objective: This study aimed at evaluating advanced parental age as a risk factor for Autism Spectrum Disorder (ASD) in an Omani cohort. Methods: Case-control study of 278 ASD cases compared with 722 sex-matched controls retrieved from the electronic records of the Developmental Paediatric Clinic, Sultan Qaboos University Hospital (SQUH) between January 2015 and June 2016. Results: ASD cases (76.6% male) were mostly diagnosed between 3-4 years of age, with more than 50% of them originating from Muscat and Batinah governorates. Compared to controls, mothers from the case group had significantly higher educational level (post-secondary education versus high school/no formal education (odds-ratio (OR)=1.62; 95% C.I. 1.20-2.19). In a multivariate logistic regression, the odds ratio of maternal age as a risk for ASD increased dramatically with advancing age category (using age<25 as a reference, OR was 3.39, 6.12, 7.86 and 13.13 for age categories 25-29, 30-34, 35-39, and ≥40 years, respectively). The ORs of advancing paternal age as a risk for ASD were also statistically significant (using age<30 as referent, OR was 2.20, 2.36, and 3.12 for age categories 30-34, 35-39 and 40-44 years); however, there was a drop in the effect with paternal age ≥ 45 years (OR=1.42; 95% C.I .64-3.15). Conclusion: Both maternal and paternal increased age were associated with a higher risk of ASD; however, the association was more pronounced and more consistent with advanced maternal age compared to paternal age. Keywords: Autism; parental age; case-control study