A Novel Likely Pathogenic Variant in the BLOC1S5 Gene Associated with Hermansky-Pudlak Syndrome Type 11 and an Overview of Human BLOC-1 Deficiencies.

Hermansky-Pudlak syndrome (HPS) is a heterogeneous disorder combining oculocutaneous albinism (OCA) and a platelet function disorder of varying severity as its most prominent features. The genes associated with HPS encode for different BLOC- (biogenesis of lysosome-related organelles complex) complexes and for the AP-3 (adaptor protein-3) complex, respectively. These proteins are involved in maturation, trafficking, and the function of lysosome-related organelles (LROs) such as melanosomes and platelet δ-granules. Some patients with different types of HPS can develop additional complications and symptoms like pulmonary fibrosis, granulomatous colitis, and immunodeficiency. A new type of HPS has recently been identified associated with genetic alterations in the BLOC1S5 gene, which encodes the subunit Muted of the BLOC-1 complex. Our aim was to unravel the genetic defect in two siblings with a suspected HPS diagnosis (because of OCA and bleeding symptoms) using next generation sequencing (NGS). Platelet functional analysis revealed reduced platelet aggregation after stimulation with ADP and a severe secretion defect in platelet δ-granules. NGS identified a novel homozygous essential splice site variant in the BLOC1S5 gene present in both affected siblings who are descendants of a consanguine marriage. The patients exhibited no additional symptoms. Our study confirms that pathogenic variants of BLOC1S5 cause the recently described HPS type 11.

Effect of Cannabidiol on Interictal Epileptiform Activity and Sleep Architecture in Children with Intractable Epilepsy: A Prospective Open-Label Study.

BACKGROUND: Cannabidiol has been shown to be effective in seizure reduction in patients with Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis. However, very little is known about its potential to reduce interictal epileptiform activity and improve sleep architecture. OBJECTIVE: The objective of this prospective study was to evaluate the influence of cannabidiol therapy on the frequency of interictal epileptiform discharges (IEDs) and sleep microstructure in a cohort of children with drug-resistant epilepsy. METHODS: Children with drug-resistant epilepsy were prospectively followed from November 2019 to January 2021 during an open-label trial of cannabidiol at a dose of 20 mg/kg/day (to a maximum of 50 mg/kg/day) and stable concomitant medication. Electroencephalograms were recorded at baseline (T0) and after 3 months (T1). Two independent raters, blinded to clinical outcome, evaluated 5-min segments of sleep stage 2 or low-noise awake state. IEDs were visually identified and rates per minute calculated. Sleep microstructure was considered improved if sleep structures were seen at T1 that were not present at T0. IED rates at T0 and T1 were compared and correlated with seizure outcome, cannabidiol dose, initial IED rate, and disease duration. RESULTS: In total, 35 children (mean ± standard deviation age 10.1 ± 0.86) were included. The IED rate at T1 was significantly lower than at T0 (19.6 ± 19.5 vs. 36.8 ± 27.2, respectively; p < 0.0001). We found a moderate correlation between IED reduction and percentage of seizure reduction compared with baseline (Pearson's r = 0.39; p = 0.02), a moderate negative correlation between IED reduction and IED rate at T0 (r = - 0.34; p = 0.04), and a trend towards a moderate negative correlation between IED reduction and disease duration (r = - 0.32; p = 0.06). Sleep was recorded in 23 patients. Sleep microstructure was initially abnormal in 56.5% of sleep recordings and improved in 84.6% of those cases. CONCLUSION: Our results strongly suggest the utility of cannabidiol in reducing IEDs and improving sleep microstructure in children with drug-resistant epilepsy. Larger controlled studies are needed to evaluate the clinical relevance of this effect in different epilepsy types. TRIAL REGISTRATION: DRKS00013177; 25 June 2019.

Expectations and knowledge of cannabidiol therapy for childhood epilepsy - A German caregiver survey.

BACKGROUND: Cannabidiol (CBD) has gained popularity among parents of children with epilepsy, even before evidence of efficacy and safety was available. The aim of our survey was to gain information about parental attitude to CBD, as well as expectations and knowledge of CBD for treatment of their child's epilepsy. METHODS: A survey using an open-access online questionnaire for parents or caregivers of children with epilepsy within German-speaking countries from March to June 2019 was used. RESULTS: Of 378 complete questionnaires (mean age of children: 11.1 (standard deviation [SD] 7.4) years), 28% (n = 106) reported previous or current CBD treatment over a mean time of 17.31 months (SD: 19.74), whereas 72% had no personal experience with CBD. Treatment was proposed by parents and not by physicians in 83% of cases and was mainly carried out with prescription-only products (71%, n = 67). Nevertheless, 29% used unregulated, artisanal products. Of all parents with previous experience, n = 77 (73%) reported that they expected CBD to be more efficient than the common antiseizure drugs (ASDs) at the beginning. Forty-five percent reported that their expectations were not met during therapy. Consistently, lack of seizure reduction was the most common reason to discontinue CBD (12/26). Of those responders without CBD experience, 93% would consider CBD for their child. However, the self-reported level of information was considered to be poor or very poor regarding efficacy (76%, n = 177), tolerance (83%, n = 191), interaction with other medication (91%, n = 211), and potential long-term effects (87%, n = 212). CONCLUSIONS: There is a huge interest in CBD but includes potentially unrealistic expectations of its efficacy and tolerance combined with a low level of information. Neuropediatricians should address parents of children with epilepsy regarding potential motivation and expectations of CBD. In addition, parental education, especially on interactions and potential side effects, is strongly recommended.

Identification of a new dysfunctional platelet P2Y12 receptor variant associated with bleeding diathesis.

Defects of the platelet P2Y12 receptor (P2Y12R) for adenosine diphosphate (ADP) are associated with increased bleeding risk. The study of molecular abnormalities associated with inherited qualitative defects of the P2Y12R protein is useful to unravel structure-function relationships of the receptor. We describe the case of 2 brothers, sons of first cousins, with lifelong history of abnormal bleeding, associated with dysfunctional P2Y12R and a previously undescribed missense mutation in the encoding gene. ADP (4-20 µM)-induced aggregation of patients' platelets was markedly reduced and rapidly reversible. Other agonists induced borderline-normal aggregation. Inhibition of vasodilator-stimulated phosphoprotein phosphorylation and prostaglandin E1-induced increase in cyclic adenosine monophosphate (cAMP) by ADP was impaired, whereas inhibition of cAMP increase by epinephrine was normal. [(3)H]PSB-0413, a selective P2Y12R antagonist, bound to a normal number of binding sites; however, its affinity, and that of the agonists ADP and 2-methylthio-adenosine-5'-diphosphate, was reduced. Patients' DNA showed a homozygous c.847T>A substitution that changed the codon for His-187 to Gln (p.His187Gln). Crystallographic data and molecular modeling studies indicated that His187 in transmembrane 5 is important for agonist and nucleotide antagonist binding and located in a region undergoing conformational changes. These studies delineate a region of P2Y12R required for normal function after ADP binding.

Early diagnosis of acquired von Willebrand Syndrome (AVWS) is elementary for clinical practice in patients treated with ECMO therapy.

AIMS: Acquired Von Willebrand syndrome (AVWS) is an acquired bleeding disorder that has been reported to aggravate bleeding complications in patients with ventricular assist devices or aortic stenosis. AVWS is characterized by the loss of the high-molecular-weight (HMW) multimers of Von Willebrand factor (VWF) with consequent impaired VWF binding to platelets and collagen. The aim of this study was to investigate the development of AVWS in patients treated with veno-venous ECMO (extracorporeal membrane oxygenation) support. METHODS: We examined the presence of AVWS in adult patients receiving ECMO support (n=18) and control subjects treated without ECMO support (n=18). The diagnosis of AVWS was made based on the ratio of collagen-binding capacity to VWF-antigen (VWF:CB/VWF:Ag) and a VWF multimeric analysis. In addition, bleeding episodes were monitored. RESULTS: All patients supported with ECMO developed AVWS. AVWS was identified in the early period after ECMO implantation, i.e. within 24 hours after ECMO implantation. In 17 patients, the VWF:CB/VWF:Ag ratio was significantly reduced and HMW multimers were severely missing, and 17 of the 18 patients developed bleeding complications and required transfusions of blood, FFP and/or platelet concentrates.In addition, nine patients without an ECMO device were investigated (prior to ECMO implantation: n=2, after ECMO explantation: n=7). CONCLUSIONS: In this study, all patients treated with ECMO support developed AVWS, and AVWS was detectable within 24 hours after ECMO implantation. However, the AVWS was reversible after ECMO explantation. Making an early diagnosis of AVWS and providing appropriate treatment may reduce the incidence of life-threatening bleeding.

Platelet dysfunction and acquired von Willebrand syndrome in patients with left ventricular assist devices.

OBJECTIVES: Unexplained bleeding events are a severe complication in patients with left ventricular assist devices (LVADs). Platelet dysfunction and acquired von Willebrand syndrome (AVWS) may contribute to bleeding tendencies. Yet, comprehensive data with respect to platelet function and AVWS in LVAD patients in terms of bleeding events are scarce. METHODS: Thirty-nine HeartMate II patients were included in this study. Data of at least two time points were available for each patient. Platelet function was analysed via light transmission aggregometry in 19 patients without LVAD, 28 in early (≤14 days) and 30 in late postimplantation states (≥30 days). Von Willebrand factor (VWF) antigen, VWF collagen binding capacity and VWF multimeric analyses were performed in 26 patients without LVAD, 39 in early and 33 in late postimplantation states to diagnose AVWS. Bleeding complications were recorded for 39 patients in the early and 33 in the late postoperative period. RESULTS: Platelet dysfunction was detectable in 18 of 19 without LVAD and in all patients following LVAD implantation. Platelet aggregation values did not change over time (without-early, P = 0.27, n = 14; early-late, P = 0.17, n = 21). AVWS was not diagnosed in patients without LVAD, except for one. On LVAD, 33 of 39 patients had AVWS in the early and all in the late period (n = 33). Bleeding events occurred in 44% of patients in the early and in 64% of patients in the late period. CONCLUSIONS: According to our data, platelet aggregation is often impaired in LVAD patients even without an implanted LVAD. Additionally, appearance of AVWS seems to be closely linked to LVAD implantation.

Shear-stress induced acquired von Willebrand syndrome in children with congenital heart disease.

OBJECTIVES: To determine the frequency and severity of acquired von Willebrand syndrome (AVWS) in children with stenotic congenital heart disease (CHD) before and after intervention. METHODS: In this single-centre prospective observational case-control study, 50 children [median age: 26 (range, 0-175) months, bodyweight: 9.5 (2.2-7.5) kg] underwent catheter interventions or cardiac surgery. A total of 26 children with high stenosis [mean gradient: 80 (range, 52-130) mmHg] represented the stenosis group and 24 without relevant stenosis (<20 mmHg) served as the control group. von Willebrand factor (VWF) was analysed with respect to quantity and function before and after corrective or palliative intervention. RESULTS: Demographic data were comparable. The stenosis group had more surgical and the control group more interventional procedures (P = 0.025). Before intervention, 13 patients from the stenosis group (50%) showed a significant reduction in VWF-multimers compared with no patients in the control group (P <0.001). Collagen binding capacity (VWF:CB) was lower in the stenosis group [0.5 (0.2-2.6) U/ml vs 0.8 (0.4-2.1) U/ml, P <0.05), as was the collagen binding capacity to antigen ratio (VWF:CB/Ag) [0.8 (0.4-1.4) U/ml vs 1 (0.4-1.7) U/ml, P <0.001). After intervention, VWF parameters normalized rapidly within the first 24 h after the procedure and showed no group differences. {VWF:CB [1.7 (0.6-3.7) vs 1.7 (0.6-4.2) U/ml, P = n.s.], VWF:CB/Ag [1.1 (0.5-2.9) vs 1.2 (0.7-2.2), P = n.s} Time in the intensive care unit, respirator time, duration of stay and bleeding before and after intervention were not significantly different. CONCLUSIONS: AVWS is detected in half of the children with high intra- or extracardiac stenoses and resolves completely after surgical or interventional repair. Even when undergoing surgery on cardiopulmonary bypass, excessive surgical site bleeding was not detected in our study patients.

Comparison of Von Willebrand factor (VWF) activity VWF:Ac with VWF ristocetin cofactor activity VWF:RCo.

INTRODUCTION: Ristocetin cofactor activity of Von Willebrand factor (VWF:RCo) and the ratio VWF:RCo to its antigen VWF:Ag are used as routine screening to estimate VWF function and to detect types of Von Willebrand disease (VWD) caused by loss of high molecular weight multimers. However, the VWF:RCo test is prone to analytic imprecisions due to various reasons. We compared an assay for VWF activity (VWF:Ac) with VWF:RCo putting emphasis on the ratios to VWF:Ag. MATERIALS AND METHODS: We evaluated 942 samples from 432 patients and evaluated three groups in detail: normal patients (normal multimers, VWF:Ag and VWF:RCo >0.5 U/ml, VWD type 1 excluded; n=258), VWD type 1 (n=76) and acquired Von Willebrand syndrome (AVWS, n=326). In addition, 30 healthy subjects were analysed. RESULTS: VWF:Ac and VWF:RCo correlated well (Pearson´s r=0.96, p<0.01), so did their ratios to VWF:Ag (Pearson´s r=0.82, p<0.01). We calculated the normal range of VWF:Ac/VWF:Ag for healthy subjects as 0.8-1.16. In comparison, the reference range (mean±2std) derived from normal patient samples was 0.73-1.14. The corresponding ranges for VWF:RCo/VWF:Ag came to 0.74-1.23 (healthy) and 0.62-1.25 (normal patients). The ratios showed similar results regarding VWD type 1. The sensitivity for AVWS was higher with VWF:Ac/VWF:Ag than with VWF:RCo/VWF:Ag (97.5% versus 84.7%). CONCLUSIONS: The data suggest that the results obtained with the VWF:Ac assay are comparable to that of the VWF:RCo assay. An AVWS was more reliably detected by VWF:Ac/VWF:Ag. We assume that the VWF:Ac assay could replace VWF:RCo for routine screening for AVWS, especially when prompt evaluation is required.

Acquired von Willebrand syndrome in patients with extracorporeal life support (ECLS).

PURPOSE: Extracorporeal life support (ECLS) is used for patients with refractory heart failure with or without respiratory failure. This temporary support is provided by blood pumps which are connected to large vessels. Bleeding episodes are a typical complication in patients with ECLS. Recently, several studies illustrated that acquired von Willebrand syndrome (AVWS) can contribute to bleeding tendencies in patients with long-term ventricular assist devices (VAD). AVWS is characterized by loss of the high molecular weight (HMW) multimers of von Willebrand factor (VWF) as a result of high shear stress and leads to impaired binding of VWF to platelets and to subendothelial matrix. Since ECLS and VAD share several features, we investigated patients with ECLS for AVWS. METHODS: We analyzed 32 patients with ECLS and 19 of them without support. To diagnose AVWS, ratios of ristocetin cofactor activity (VWF:RCo) and collagen binding capacity (VWF:CB) to VWF antigen (VWF:Ag) were employed in conjunction with multimeric analysis. RESULTS: Reduced VWF:RCo/VWF:Ag ratios were identified in 28 ECLS patients. Furthermore, VWF:CB/VWF:Ag ratios were decreased in 31 patients. HMW multimers of VWF were missing in the same 31 patients. Thus, 31 of 32 ECLS patients presented with AVWS. Twenty-two of the 32 patients suffered from bleeding complications. Without support, AVWS was not detectable in any analyzed patient. CONCLUSION: Our data indicate that AVWS is a typical disorder in patients with ECLS. We hypothesize that AVWS could contribute to aggravation of bleeding tendencies in ECLS patients.

Acquired Von Willebrand syndrome is an early-onset problem in ventricular assist device patients.

OBJECTIVE: Acquired Von Willebrand syndrome (AVWS) can contribute to bleeding complications in patients with ventricular assist devices (VADs). AVWS results from shear stress, which causes unfolding of the high-molecular-weight (HMW) multimers of Von Willebrand factor (VWF) with subsequent cleavage. Loss of the HMW multimers of VWF is the leading finding in AVWS. In consequence, binding of VWF to collagen and to platelets is impaired. The onset of AVWS after VAD implantation is not yet determined. We examined VAD patients for presence of an AVWS in the early, intermediate, and late phase after VAD implantation. METHODS: Patients with a biventricular Thoratec-PVAD(®) (BVAD, n = 6) or a left-ventricular HeartMateII(®) (HMII, n = 11) were analyzed prior to VAD implantation and after 1, 3, 14, 30, and 60 days. Diagnosis of AVWS based on VWF:ristocetin cofactor activity/VWF:VWF antigen (VWF:RCo/VWF:Ag), collagen-binding capacity:VWF antigen (VWF:CB/VWF:Ag), and multimeric analysis. In addition, we analyzed the number of bleeding episodes, which required surgical intervention. RESULTS: No patient had an AVWS prior to VAD implantation. An AVWS was identified already in the very early postoperative period, that is, in almost all patients on the first day and in all patients on the third day. The AVWS was also detected in the majority of patients in the further course. Nine of all 17 patients suffered bleeding complications and required a total of 25 interventions due to hemorrhages. Forty percent of re-interventions were carried out within the first 10 days after implantation; five of these were necessary within the first 24h. CONCLUSION: The AVWS is present already in the early postoperative phase after VAD implantation. Therefore, reduced shear stress has to be an important feature of newly developed assist devices in the future.

Acquired von Willebrand syndrome in patients with ventricular assist device or total artificial heart.

Unexplained bleeding episodes are associated with ventricular assist devices (VAD) and can occur in part due to acquired von Willebrand syndrome (AVWS). AVWS is characterised by loss of high molecular weight (HMW) multimers of von Willebrand factor (VWF) and decreased ratios of collagen binding capacity and ristocetin cofactor activity to VWF antigen. Loss of multimers can occur as VWF is subjected to increased shear stress, which occurs in presence of VADs. We studied 12 patients who required mechanical support of their native heart for terminal cardiac insufficiency. Nine patients underwent placement of a VAD, while three underwent placement of a total artificial heart (TAH), which is connected directly to heart and large cardiac vessels without cannulas. Within one day of VAD implantation, four of five patients evaluated demonstrated loss of HMW multimers and impaired VWF function. AVWS was present within two weeks of implantation in eight of nine patients, and in all seven tested patients after >/=3 months. Patients with different VAD types developed varying severities of AVWS. After VAD explantation, HMW multimers were detectable and VWF function normalised in all patients. AVWS was not observed in the TAH patients studied. Our findings demonstrate that patients with an implanted VAD experience a rapid onset of AVWS that is quickly and completely reversed after device explantation. In addition, TAH patients do not develop AVWS. These results suggest that shear stress associated with exposure of blood to VAD cannulas and tubes may contribute to the development of AVWS.