Key Points Developed a targeted sequencing platform covering 63 genes linked to heritable bleeding, thrombotic, and platelet disorders. The ThromboGenomics platform provides a sensitive genetic test to obtain molecular diagnoses in patients with a suspected etiology.

BackgroundHeritable bleeding and platelet disorders (BPD) are heterogeneous and frequently have an unknown genetic basis. The BRIDGE-BPD study aims to discover new causal genes for BPD by high throughput sequencing using cluster analyses based on improved and standardised deep, multi-system phenotyping of cases.MethodsWe report a new approach in which the clinical and laboratory characteristics of BPD cases are annotated with adapted Human Phenotype Ontology (HPO) terms. Cluster analyses are then used to characterise groups of cases with similar HPO terms and variants in the same genes.ResultsWe show that 60% of index cases with heritable BPD enrolled at 10 European or US centres were annotated with HPO terms indicating abnormalities in organ systems other than blood or blood-forming tissues, particularly the nervous system. Cases within pedigrees clustered closely together on the bases of their HPO-coded phenotypes, as did cases sharing several clinically suspected syndromic disorders. Cases subsequently found to harbour variants in ACTN1 also clustered closely, even though diagnosis of this recently described disorder was not possible using only the clinical and laboratory data available to the enrolling clinician.ConclusionsThese findings validate our novel HPO-based phenotype clustering methodology for known BPD, thus providing a new discovery tool for BPD of unknown genetic basis. This approach will also be relevant for other rare diseases with significant genetic heterogeneity.Electronic supplementary materialThe online version of this article (doi:10.1186/s13073-015-0151-5) contains supplementary material, which is available to authorized users.

Summary This report presents seven children with congenital thrombotic thrombocytopenic purpura (TTP). Six had a history of severe neonatal unconjugated hyperbilirubinaemia and thrombocytopenia. The seventh child had no neonatal problems but has suffered three episodes of acute TTP. The subsequent clinical course of the children varied. Five had a relapsing–remitting course and one had chronic microangiopathic haemolytic anaemia. The five oldest children initially received plasma infusions but, because of viral safety issues and easier administration, they now receive intermediate purity US‐sourced plasma‐derived factor VIII concentrate: BPL 8Y. Effective prophylaxis and treatment is possible in congenital TTP using BPL 8Y.

Next-generation sequencing has been invaluable in the elucidation of the genetic etiology of many subtypes of intellectual disability in recent years. Here, using exome sequencing and whole-genome sequencing, we identified three de novo truncating mutations in WAS protein family member 1 (WASF1) in five unrelated individuals with moderate to profound intellectual disability with autistic features and seizures. WASF1, also known as WAVE1, is part of the WAVE complex and acts as a mediator between Rac-GTPase and actin to induce actin polymerization. The three mutations connected by Matchmaker Exchange were c.1516C>T (p.Arg506Ter), which occurs in three unrelated individuals, c.1558C>T (p.Gln520Ter), and c.1482delinsGCCAGG (p.Ile494MetfsTer23). All three variants are predicted to partially or fully disrupt the C-terminal actin-binding WCA domain. Functional studies using fibroblast cells from two affected individuals with the c.1516C>T mutation showed a truncated WASF1 and a defect in actin remodeling. This study provides evidence that de novo heterozygous mutations in WASF1 cause a rare form of intellectual disability.

Background:As most children with acute lymphoblastic leukaemia (ALL) achieve long-term survival, minimising late effects of treatment is a priority. Acute lymphoblastic leukaemia survivors treated historically with protocols including cranial irradiation demonstrate increased weight gain.Methods:We retrospectively studied all 134 patients treated on the MRC/UKALL97 protocol (without cranial irradiation as standard therapy) at a single centre, with 77 inclusions. Height-, weight- and body mass index (BMI) standard-deviation scores (SDS) were recorded at diagnosis and annually until 3 years out (YO) from end of treatment (EoT); changes across time were explored using a univariate model (significance P⩽0.001 to account for multiple comparisons).Results:Whole-group height SDS was lower from 1 year into treatment until 2 YO, whereas weight- and BMI-SDS remained higher until 3 YO. In females, height-SDS was lower until EoT, but higher weight- and BMI-SDS persisted until 3 YO. In males, height-SDS was lower at EoT and at 2 YO; differences in BMI-SDS had resolved by 2 YO. By WHO criteria, more patients were overweight or obese at 3 YO than at diagnosis (P=0.01).Conclusion:Survivors of childhood ALL, particularly females, exhibit adverse changes in height-, weight- and BMI-SDS, which arise during treatment and persist into follow-up. Patients should be supported with appropriate dietary and lifestyle advice during ALL treatment and follow-up, which may minimise these changes and reduce associated long-term morbidity.

Introduction Nuwiq® (Human‐cl rhFVIII) is a fourth generation recombinant FVIII, produced in a human cell line, without chemical modification or protein fusion. No inhibitors developed in studies with Nuwiq® in 201 previously treated patients with haemophilia A (HA). The immunogenicity, efficacy and safety of Nuwiq® in previously untreated patients (PUPs) with severe HA are being assessed in the ongoing NuProtect study. Methods The study, conducted across 38 centres worldwide, is evaluating 110 true PUPs of all ages and ethnicities enrolled for study up to 100 exposure days (EDs) or 5 years maximum. The primary objective is to assess the immunogenicity of Nuwiq® (inhibitor activity ≥0.6 BU) using the Nijmegen‐modified Bethesda assay at a central laboratory. Results Data for 66 PUPs with ≥20 EDs from a preplanned interim analysis were analysed. High‐titre (HT) inhibitors developed in 8 of 66 patients after a median of 11.5 EDs (range 6‐24). Five patients developed low‐titre inhibitors (4 transient). The cumulative incidence (95% confidence interval) was 12.8% (4.5%, 21.2%) for HT inhibitors and 20.8% (10.7%, 31.0%) for all inhibitors. During inhibitor‐free periods, median annualized bleeding rates during prophylaxis were 0 for spontaneous bleeds and 2.40 for all bleeds. Efficacy was rated as “excellent” or “good” in treating 91.8% of bleeds. Efficacy of surgical prophylaxis was “excellent” or “good” for 8 (89%) procedures and “moderate” for 1 (11%). No tolerability concerns were evident. Conclusion These interim data show a cumulative incidence of 12.8% for HT inhibitors and convincing efficacy and tolerability in PUPs treated with Nuwiq®.

Introduction FVIII inhibitor development is the most serious contemporary treatment complication in haemophilia A, particularly in previously untreated patients (PUPs). No inhibitors developed in clinical trials in previously treated patients treated with simoctocog alfa (Nuwiq), a fourth-generation recombinant FVIII produced in a human cell line. Methods The NuProtect study investigated the immunogenicity of simoctocog alfa in PUPs. NuProtect was a prospective, multinational, open-label, non-controlled, phase III study. PUPs with severe haemophilia A (FVIII:C <1%) of any age and ethnicity were treated with simoctocog alfa for 100 exposure days or a maximum of 5 years. Patients were true PUPs without prior exposure to FVIII concentrates or blood components. Inhibitor titres were measured with the Nijmegen-modified Bethesda assay; cut-off for positivity was 0.6 BU mL−1 (≥0.6 to <5 low-titre, ≥5 high titre). Results A total of 108 PUPs with a median age at first treatment of 12.0 months (interquartile range: 8.0–23.5) were treated with simoctocog alfa. F8 mutation type was known for 102 patients (94.4%) of whom 90 (88.2%) had null F8 mutations and 12 (11.8%) had non-null mutations. Of 105 PUPs evaluable for inhibitor development, 28 (26.7%) developed inhibitors; 17 high titre (16.2%) and 11 low titre (10.5%). No PUPs with non-null F8 mutations developed inhibitors. Conclusion In the NuProtect study, the rate of inhibitor development in PUPs with severe haemophilia A treated with simoctocog alfa was lower than the rate reported for hamster-cell-derived recombinant factor VIII products in other recent clinical trials. No inhibitors were reported in PUPs with non-null F8 mutations.

Thrombotic thrombocytopenic purpura (TTP) in children is rare and is often thought to be due to congenital ADAMTS13 deficiency. We report seven new cases of noncongenital TTP in children and adolescents and perform a review of the literature where ADAMTS13 assays have been performed in paediatric acquired TTP. All new cases were female and the median age was 13 years. Presenting clinical features included bruising/petechiae or bleeding, fever, neurological, and renal impairment. Median Hb and platelet counts on admission were 66 g/l and 10 x 10(9)/l respectively. Two cases had raised Troponin T levels and one had an abnormal ECG. All cases had ADAMTS13 activity less than 5% and an inhibitor to ADAMTS13. The median number of plasma exchange to remission was 22.5. Six cases received rituximab. Three achieved normal ADAMTS13 activity and remain in remission. Two had persistently low ADAMTS13 activity with high anti-ADAMTS13 IgG levels and one of these relapsed. One had moderately reduced levels of ADAMTS13 in remission with no inhibitor, however, a fall in ADAMTS13 activity and increase in anti-ADAMTS13 IgG heralded clinical relapse. The literature review identified 12 acquired cases showing low ADAMTS13 activity and inhibition of ADAMTS13 (in 95%). In children and adolescents TTP may be due to acquired deficiency of ADAMTS13, associated with an inhibitor/Anti-ADAMTS13 IgG antibodies. Treatment of acquired disease requires PEX and usually immunosuppressive treatment. Rituximab appears to be an effective adjunctive treatment modality.