Postanalytical considerations that may improve the diagnosis or exclusion of haemophilia and von Willebrand disease

Post-analytical Issues in Hemostasis and Thrombosis Testing: An Update

There are typically three phases identified as contributing to the total testing process. The preanalytical phase starts with the clinician and the patient, when laboratory testing is being considered. This phase also includes decisions about which tests to order (or not), patient identification, blood collection, blood transport, sample processing, and storage to name a few. There are many potential failures that may occur in this preanalytical phase, and these are the topic of another chapter in this book. The second phase, the analytical phase, represents the performance of the test, which is essentially covered in various protocols in this book and the previous edition. The third is the post-analytical phase, which is what occurs after sample testing, and is the topic of the current chapter. Post-analytical issues are generally related to reporting and interpretation of test results. This chapter provides a brief description of these events, as well as guidance for preventing or minimizing post-analytical issues. In particular, there are several strategies for improved post-analytical reporting of hemostasis assays, with this providing the final opportunity to prevent serious clinical errors in patient diagnosis or management.

Results of genetic analysis of 11 341 participants enrolled in the My Life, Our Future hemophilia genotyping initiative in the United States

BACKGROUND

Hemophilia A (HA) and hemophilia B (HB) are rare inherited bleeding disorders. Although causative genetic variants are clinically relevant, in 2012 only 20% of US patients had been genotyped.

OBJECTIVES

My Life, Our Future (MLOF) was a multisector cross-sectional US initiative to improve our understanding of hemophilia through widespread genotyping.

METHODS

Subjects and potential genetic carriers were enrolled at US hemophilia treatment centers (HTCs). Bloodworks performed genotyping and returned results to providers. Clinical data were abstracted from the American Thrombosis and Hemostasis Network dataset. Community education was provided by the National Hemophilia Foundation.

RESULTS

From 2013 to 2017, 107 HTCs enrolled 11 341 subjects (68.8% male, 31.2% female) for testing for HA (n = 8976), HB (n = 2358), HA/HB (n = 3), and hemophilia not otherwise specified (n = 4). Variants were detected in most male patients (98.2%% HA, 98.1% HB). 1914 unique variants were found (1482 F8, 431 F9); 744 were novel (610 F8, 134 F9). Inhibitor data were available for 6986 subjects (5583 HA; 1403 HB). In severe HA, genotypes with the highest inhibitor rates were large deletions (77/80), complex intron 22 inversions (9/17), and no variant found (7/14). In severe HB, the highest rates were large deletions (24/42). Inhibitors were reported in 27.3% of Black versus 16.2% of White patients.

CONCLUSIONS

The findings of MLOF are reported, the largest hemophilia genotyping project performed to date. The results support the need for comprehensive genetic approaches in hemophilia. This effort has contributed significantly towards better understanding variation in the F8 and F9 genes in hemophilia and risks of inhibitor formation.

Resolving Differential Diagnostic Problems in von Willebrand Disease, in Fibrinogen Disorders, in Prekallikrein Deficiency and in Hereditary Hemorrhagic Telangiectasia by Next-Generation Sequencing

Diagnosis of rare bleeding disorders is challenging and there are several differential diagnostics issues. Next-generation sequencing (NGS) is a useful tool to overcome these problems. The aim of this study was to demonstrate the usefulness of molecular genetic investigations by summarizing the diagnostic work on cases with certain bleeding disorders. Here we report only those, in whom NGS was indicated due to uncertainty of diagnosis or if genetic confirmation of initial diagnosis was required. Based on clinical and/or laboratory suspicion of von Willebrand disease (vWD, n = 63), hypo-or dysfibrinogenemia (n = 27), hereditary hemorrhagic telangiectasia (HHT, n = 10) and unexplained activated partial thromboplastin time (APTT) prolongation (n = 1), NGS using Illumina platform was performed. Gene panel covered 14 genes (ACVRL1, ENG, MADH4, GDF2, RASA1, F5, F8, FGA, FGB, FGG, KLKB1, ADAMTS13, GP1BA and VWF) selected on the basis of laboratory results. We identified forty-seven mutations, n = 29 (6 novel) in vWD, n = 4 mutations leading to hemophilia A, n = 10 (2 novel) in fibrinogen disorders, n = 2 novel mutations in HHT phenotype and two mutations (1 novel) leading to prekallikrein deficiency. By reporting well-characterized cases using standardized, advanced laboratory methods we add new pieces of data to the continuously developing “bleeding disorders databases”, which are excellent supports for clinical patient management.

Heavy Menstrual Bleeding in Adolescent Girls

Heavy menstrual bleeding (HMB) is a common complaint among adolescent girls. It reflects an abnormal volume of blood loss during the menstrual cycle. Abnormal uterine bleeding can manifest as HMB but includes menstrual irregularity. In many cases, immaturity of the hypothalamic-pituitary-ovarian axis or hormonal conditions like polycystic ovarian syndrome leading to anovulatory cycles are the underlying cause for heavy menses. However, in girls with HMB, especially those not responding to the usual hormonal attempts to manage HMB, an underlying bleeding disorder should be considered. Up to 62% of adolescents with HMB have a bleeding disorder, many without anemia at presentation. Evaluation for HMB in an adolescent girl should include referrals to an adolescent medicine specialist or gynecologist and pediatric hematologist. [Pediatr Ann. 2020;49(4):e163-e169.].