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CDC Webinar:  Understanding Factor Levels and Bleeding in Hemophilia Genotype-Positive Females

Hemophilia A and B are rare inherited bleeding disorders caused by deficiencies in coagulation factor VIII (FVIII) or factor IX (FIX). Nearly all people with hemophilia A or B have an identifiable DNA change in the F8 or F9 genes, respectively. The inheritance of hemophilia has historically been described as a “recessive” X-linked pattern that only affects males. However, females who have one or more hemophilia-causing genotypes can also have bleeding and hemophilia. The misperception of hemophilia as a male-only disorder has led to clinical definitions and descriptions of disease informed by the male experience and under-recognition of the healthcare needs of females with hemophilia. 

There is growing evidence that hemophilia genotype-positive females can commonly experience excessive bleeding, delays in diagnosis, undertreatment, and poor quality of life. Different than in males, coagulation factor levels do not correlate well with bleeding, and some genotype-positive females experience excessive bleeding even with factor levels within the normal reference range. Genetic testing, factor levels, and bleeding symptom assessment are all important in making a diagnosis of hemophilia, symptomatic carrier, or asymptomatic carrier in females. Females also commonly experience heavy menstrual bleeding and are at high risk for postpartum hemorrhage. However, the causes of excessive reproductive tract bleeding are not well understood. 

In this webinar, Dr. Johnsen will discuss various considerations for females who have hemophilia genotypes, including inheritance patterns, factor levels, bleeding manifestations, and nomenclature for diagnosis of hemophilia. She will also describe the Hemophilia A Research Program (HARP), a new study seeking to better understand the hemophilia bleeding risk in pregnancy and identify the causes of inhibitor formation in early childhood.

Learning Objectives:

  1. Describe the inheritance patterns of hemophilia A and B.
  2. Understand that females with a hemophilia-causing genotype can have excessive bleeding and hemophilia, regardless of factor level.
  3. List criteria under the current nomenclature for diagnosis of 

This webinar is shared as part of HFA’s cooperative agreement with the CDC. This webinar is free and open to healthcare providers, pharmacists, and public health researchers who desire more information about blood disorders. Advance registration is required, and the number of attendees is limited. 

For more information contact:


May 16 2024


2:00 pm - 3:00 pm

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  • Dr. Jill Johnsen
    Dr. Jill Johnsen

    Dr. Johnsen is a physician scientist with expertise in classical (benign) hematology. She is an Associate Professor of Medicine at the University of Washington and sees patients at the Washington Center for Bleeding Disorders. She studies the genetics and biology of variation in clotting factors and blood groups (blood types), with emphasis on coagulation factor VIII (FVIII), factor IX (FIX), and von Willebrand factor (VWF). She is particularly interested to leverage these research efforts towards better understanding how bleeding uniquely impacts females. Her research program is dedicated to improving the diagnosis and care of patients with blood disorders through advancement of our basic understanding of the underlying biology and through the translation of new knowledge and laboratory innovations to improve clinical testing. Her research leverages new technologies, including targeted and whole genome next generation DNA sequencing, multi-omics, long-read sequencing, and new and novel molecular methods. In vitro functional studies, including large scale deep mutational scanning of genes of interest in mammalian cell display systems, will inform and improve interpretation of the functional significance of DNA variants discovered in hemophilia.

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