This site is an educational service brought to you by BioMarin. No gene therapies for haemophilia A or B have been approved for use or determined to be safe or effective.


There’s a lot of information out there about genetics and gene therapy, but not all of it is clear and some may be incorrect or misleading. Below are some resources for you to use when you’re ready to further explore the future of gene therapy research.


HemDifferently Brochure

A guide to better understand the science behind gene therapy research

HaemDifferently Brochure

A guide to better understand the science
behind gene therapy research



HemDifferently Brochure

An electronic library of gene therapy education resources

Gene Therapy Resources




  • Adeno-associated virus

    Any of several viruses that enter the nucleus of a host cell but are dependent on co-infection with an adenovirus or herpesvirus for their replication. They infect a wide range of hosts but do not appear to cause disease and are being researched in gene therapy as vectors to introduce genes into cells.

  • Adenovirus

    Causes mild to severe illness, though serious illness is less common. Common symptoms include common cold, sore throat, bronchitis, pneumonia, diarrhoea, pink eye and fever. Adenoviruses are usually spread from an infected person to others through close personal contact, coughing and sneezing, and touching an object or surface with adenoviruses on it, then touching your mouth, nose or eyes before washing your hands.

  • Antibody

    A blood protein created in response to a substance (antigen) not recognised by the body. Antibodies then bind to specific antigens, helping to destroy them. Some antibodies destroy antigens directly. Others make it easier for white blood cells to destroy the antigen.

  • Cell

    The fundamental, structural and functional unit of living organisms. In biology, a cell is the smallest unit that can live on its own. All living organisms and the tissues of the body are made of cells. A cell has three main parts: the cell membrane, the nucleus and the cytoplasm.

  • Chromosome

    A structure found in animal cells containing a linear thread of DNA, which transmits genetic information. Humans normally have 46 chromosomes (23 pairs) in each cell.

  • Cystic fibrosis

    A genetic disease that causes progressive, persistent lung infections that limit the ability to breathe. Genetically, someone must inherit two copies of the cystic fibrosis transmembrane conductance regulator gene that contain mutations – one copy from each parent – to have cystic fibrosis.

  • DNA (deoxyribonucleic acid)

    The molecular basis of heredity present in humans and almost all other organisms. Nearly every cell in a person’s body contains some DNA.

  • Down’s syndrome

    A genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. Down’s syndrome causes lifelong intellectual disability and developmental delays. It’s the most common genetic chromosomal disorder and cause of learning disabilities in children.

  • Ex vivo

    From the Latin, meaning “out of the living”, ex vivo means something which takes place outside an organism. In science, ex vivo refers to experimentation or measurements done in or on tissue from an organism in an external environment with minimal alteration of natural conditions.

  • Factor VIII

    The factor VIII gene provides instructions for making a protein called coagulation factor VIII. Coagulation factors are essential for the formation of stable blood clots. Factor VIII is absent or inactive in people with haemophilia A.

  • Factor IX

    The factor IX gene provides instructions for making a protein called coagulation factor IX. Coagulation factors are essential for the formation of blood clots. Factor IX is absent or inactive in people with haemophilia B.

  • Gene

    A part of a DNA molecule, usually located on a chromosome, that is the functional unit of inheritance controlling the transmission and expression of one or more traits from parent to child.

  • Genetics

    The study of genes and their heredity. Also, a branch of biology that deals with the heredity and variation of organisms.

  • Genome

    An organism’s complete set of genetic material. It contains all of the instructions needed for the organism to function. In people, every cell that has a nucleus contains a copy of the entire genome.

  • Haemophilia

    A bleeding disorder that slows the blood clotting process. People with haemophilia can experience both spontaneous and prolonged bleeding following an injury. Serious complications can result from bleeding into the joints, muscles, brain or other internal organs. The major types of this condition are haemophilia A (factor VIII deficiency) and haemophilia B (factor IX deficiency).

  • Huntington disease

    An inherited disease that causes the progressive breakdown (degeneration) of nerve cells in the brain. Huntington disease has a broad impact on a person’s functional abilities and usually results in movement, thinking (cognitive) and psychiatric disorders.

  • Lentivirus

    A retrovirus that causes persistent infection that typically results in chronic, progressive, usually fatal disease in both humans and animals. In humans, human immunodeficiency virus (HIV) may be the most recognisable lentivirus.

  • Monogenic conditions

    Monogenic conditions, such as haemophilia, are caused by a single gene not working properly. The cause of the malfunction may be present in one or both chromosomes inherited from the parents.

  • Mutation

    A change in the structure of a gene that then becomes a variant form that may be passed along to future generations. It is caused by the alteration of single base units in DNA, or the deletion, insertion or rearrangement of larger sections of genes or chromosomes.

  • Nucleotide bases

    An organic molecule that is the building block of DNA and ribonucleic acid (RNA).

  • Nucleus

    The part of a cell that contains the chromosomes. The nucleus has a membrane around it and is where RNA is made from the DNA in the chromosomes.

  • Protein

    A group of amino acids joined together that perform various biological functions. Examples include enzymes, hormones and antibodies.

  • Vector

    A vector is a means being investigated in clinical trials by which a functional gene used in gene therapy is transported to a cell. A vector can be viral or nonviral.

  • Vector shedding

    The release of the vector/genetic materials through secretions and/or excrement of the patient. Assessment of shedding can be used to understand the potential risk associated with transmission to third parties and the potential risk to the environment.