Letter to the Editor 853 This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

Platelet-type von Willebrand disease (PT-VWD) is a rare bleeding disorder with an intrinsic defect in platelets rather than von Willebrand factor (VWF), but has clinical and laboratory features similar to the more common type 2B VWD. The intriguing nature of the pathophysiology and molecular genetics of PT-VWD has created lengthy debate in literature regarding its discrimination from type 2B VWD, and essentially confirming DNA analysis as the gold standard in diagnosis and revealing pathologic mutations. In this report we identify a novel Asp235Tyrmutation in the GP1BA gene of two Iranian patients showing the PT-VWD phenotype who were originally misdiagnosed as type 2B VWD. By structural modelling of the mutant by introducing Tyr235 into the available crystal structure of the glycoprotein (GP)Ibα N-terminal domain, we observed the mutant Tyr235 generates a hydrophobic tip to the extended β-switch loop of GPIbα. Further modelling of the resulting complex with VWFA1 indicates this could result in an enhanced interface compared to wild-type Asp235. This data provides an update to the present knowledge about this rare disorder, and confirms the necessity of genetic testing for accurate diagnosis, and the importance of studying natural mutations to better understand molecular aspects of GPIbα-VWFA1 interaction.

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Introduction Congenital fibrinogen disorders (CFDs) comprise the quantitative and qualitative fibrinogen molecule abnormalities that are caused by fibrinogen gene mutations. The objective of this cohort research was to study the molecular and clinical profiles of patients with CFDs. Materials and methods Genomic DNA Sanger sequencing of 14 Iranian patients was performed to determine CFDs‐causing mutations. The disorders were diagnosed by routine and specific (fibrinogen antigen and functional assay) coagulation tests, and clinical data were obtained from medical records. Molecular dynamics (MD) simulations were performed to investigate the effect of missense mutation on the protein structure. Results Thirteen out of 14 patients had afibrinogenemia while the remaining patient had dysfibrinogenemia. Umbilical cord bleeding was the most common clinical presentation (n: 9, ~70%) which led to the diagnosis of afibrinogenemia, while menorrhagia led to the diagnosis of dysfibrinogenemia. Six homozygous mutations were identified in afibrinogenemia: three previously described variants in FGA (p.Trp52Ter, p.Ser312AlafsTer109 and p.Gly316GlufsTer105), one in FBG (p.Gly430Asp), and two novel mutations in FGB (p.Gly430Arg) and FGG (p.His366ThrfsTer40), while the FGA (p.Arg38Thr) heterozygous mutation was identified in dysfibrinogenemia. MD simulation indicated that the FGA p. Arg38Thr mutation probably interferes with polymerization of fibrin monomers. Conclusions In Iran, with its high rate of consanguinity, autosomal recessive afibrinogenemia with severe clinical presentations is relatively common due to heterogeneous molecular defects.

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Coronavirus disease 2019 (COVID-19) is a new medical challenge for all individuals, especially for those with underlying disorders, such as congenital bleeding disorders (CBDs). Therefore, the pandemic might significantly change the behaviour of patients with CBDs and results in some challenges. In the present study, we assessed the main challenges of COVID-19 infection to patients with CBDs. Data were collected from medical files and interviews of patients with CBDs who had COVID-19 infection. Follow-ups were performed on patients who had active severe acute respiratory syndrome coronavirus 2 infection between April and October 2020. All patients were interviewed by an expert in order to collect the pertinent data. Some questions were about patients’ preventive behaviors and feelings prior to infection, and some were about the consequences of infection on patients’ replacement therapy and bleeding management. Among 25 patients, infection and death of loved ones (n: 7, 28%), and their own (n: 5, 20%) or family members’ (n: 1, 4%) infection, and the resulting economic burden (n: 2, 8%) were main concerns. Six patients experienced depression during the pandemic. The pandemic caused all severely affected patients but one (n: 11, 92%) to abandon replacement therapy. However, two received on-demand therapy after exacerbation of their bleeding. Only one (25%) of four patients on prophylaxis received in-home therapy, whereas the others (75%) abandoned prophylaxis. It seems that COVID-19 infection has great consequences on the lives of patients with CBDs, causing some to take dangerous actions, such as abandonment of their treatment. Healthcare systems, and healthcare providers, should have an appropriate strategy for management of patients with CBDs that prevents infection and provides timely replacement therapy.

Congenital factor X (FX) deficiency is an extremely rare, bleeding disorder with an estimated incidence of one per 1 million. Patients with severe FX deficiency (FX:C < 1%) demonstrate a wide spectrum of serious clinical presentations, including hemarthrosis, hematoma, gastrointestinal (GI) bleeding, intracranial hemorrhage (ICH), and umbilical cord bleeding. 1 In fact, severe FX deficiency, with a high rate of life-threatening bleeding, is the second-most severe, rare coagulation factor deficiency (RCFD) after FXIII deficiency. 1,2 Although homozygotes are at risk of severe bleeding, heterozygotes usually are asymptomatic, but postsurgical bleeding or bleeding after childbirth may occur. 1,2 Other risk factors can increase the risk of bleeding in FX deficiency, and coronavirus disease 2019 (COVID-19), a new medical challenge, could affect the patient's bleeding or thrombotic tendency. 3 COVID-19, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an enormous challenge for everyone, especially for those with underlying risk factors such as cardiovascular disease, diabetes, obesity, and renal failure. Age and male sex are other risk factors. 4 Limited data are available regarding the effect of COVID-19 on patients with congenital bleeding disorders (CBDs), particularly RCFDs. 5 It has been shown that hypercoagulability-related adverse consequences are less common among patients with CBDs, at least in those with moderate-to-severe deficiency, but further studies, including our ongoing work on a large number of patients, are required. 5 Although there are several