INTRODUCTION:Personalised pharmacokinetics (PK) using Bayesian analysis with limited sampling is assumed to help to optimise prophylaxis in haemophilia A (HA) patients. MATERIALS AND METHODS:Our prospective, observational study analysed the influence of PK parameters on clinical variables (bleeding rates, joint status, adherence, and consumption) using myPKFiT® in a cohort of twenty-one severe and moderate HA patients on prophylaxis with recombinant FVIII (Advate®) in two periods of one year, the first before PK-based tailoring and the second after PK-guided prophylaxis. Intra-individual and inter-individual coefficients of variation (CV) of half-life (t1/2) were calculated. RESULTS:A total of 73 PK estimations were performed in both periods, resulting in 17.2% inter-individual CV in mean t1/2, and 4.9% intra-individual CV. Before PK-based tailoring a significant association between joint bleeds and t1/2 was found (P = 0.010), especially in patients with short t1/2. This finding was reproduced (P = 0.013) after withdrawal of two patients with bleeding phenotype related to their advanced arthropathy but normal t1/2 and trough levels. Patients with joint bleeds weighed less (P = 0.039) and required higher doses (P = 0.032) than patients with zero joint bleeds. These associations were not observed in the second period after the adoption of PK-guided prophylaxis. There were no differences between the two periods, although a tendency to fewer spontaneous bleeds was suggested after PK-based tailoring. CONCLUSIONS:PK-guided prophylaxis facilitates an adequate level of bleeding control in patients with HA, maintaining clinical variables and patient convenience in an integrative manner, without increasing FVIII consumption.

Inherited bleeding coagulation disorders (IBCDs) have a powerful diagnostic tool in next generation sequencing (NGS) that not only offers confirmation of diagnosis but also aids in genetic counselling, prenatal diagnosis and helps to predict the clinical course and follow-up of a disease. In our group, targeted-NGS using a Custom SureSelect QXT Panel (Agilent Technologies, Inc., Santa Clara, CA, USA) was designed to screen for causal variants in 40 genes related with the coagulation cascade. In this work, we used NGS for screening all the coding and intronic boundary regions of F5 gene in two patients affected by factor V (FV) deficiency (parahemophilia). Two new mutations were found: c.4745A>G (p.Tyr1582Cys, NM_000130.4) and c.1999_2002dupAATT (p.Ser668ter; NM_000130.4), both located in exon 13 of the F5 gene. We designated them Valencia-1 and Valencia-2 respectively. Valencia-1 could provoke loss of the fifth cupredoxin domain of the FV, and would be responsible for its defective activity. Valencia-2 prematurely stops the translation of mRNA, resulting in a truncated FV protein which lacks completely the B domain and the light chain. NGS has permitted to describe an increasing number of FV deficiency-causing mutations and a better understanding of FV's structure and function. The description of deficiency-causing mutations will continue to increase our knowledge of the functional residues of FV, as well as those which are involved in the correct folding of the protein. In this sense, NGS is a useful tool for studying IBCDs, as permits studying the whole coagulation cascade at once and gives a global view of the patient's genetic background.

We read with interest the study done by Loomans et al (1); wherein the authors have found that out of 148 deceased mild and moderate hemophilia patients, 62 (42%) expired due to excessive bleeding i.e. due to the disorder itself and out of these 12% died of intracranial (IC) bleed. Thus, the authors rightly conclude that non-severe hemophilia A patients also have an increased risk of death due to IC bleed and thus demonstrating the need for specialized care for these patients. India harbors the second highest number of patients with hemophilia globally, majority belonging to the poverty-stricken section (2). This article is protected by copyright. All rights reserved.

Essentials Factor VIII levels vary in mild and moderate hemophilia A (MHA) patients with the same mutation. We aimed to estimate the variation and determinants of factor VIII levels among MHA patients. Age and genotype explain 59% of the observed inter‐individual variation in factor VIII levels. Intra‐individual variation accounted for 45% of the variation in the three largest mutation groups.