Dogs with the bleeding disorder haemophilia A have been successfully treated by gene therapy, according to US scientists.

Two of three dogs given the experimental treatment remain free of severe symptoms more than two years on, they write inNature Communications.

Haemophilia A is a bleeding disorder which affects one in 10,000 men.

Gene therapy may be suitable for human treatment for bleeding disorders in 10 years, says the Haemophilia Society.


Bleeding disorders


  • The two most common types of haemophilia are haemophilia A and haemophilia B, although haemophilia A accounts for most cases
  • Haemophilia A is a bleeding disorder caused by deficiency of clotting factor VIII
  • The vast majority of cases are inherited and in men
  • Symptoms include spontaneous bleeding into joints, especially the knees, ankles and elbows
  • There is no cure for haemophilia, but with treatment a person with the condition can usually have a good quality of life
  • In recent decades genetically engineered clotting factor medications have been developed for bleeding problems
  • These medications are given as an injection


People with haemophilia A have an error in their genetic code, which means they cannot produce a protein called Factor VIII, which helps in blood-clotting.


Researchers in the US and France studied three dogs with a disorder similar to human haemophilia A.


They used a virus to carry the normal gene for factor VIII into platelets, the blood cells involved repairing damaged blood vessels.


More than two years after the gene therapy, two of the three dogs remained free of serious internal bleeding.


Lead researcher Dr David Wilcox of the Medical College of Wisconsin, Milwaukee, said the study could ultimately improve the quality of life of patients affected by haemophilia A.


Haemophilia patients usually suffer internal bleeding several times a year and have to have regular injections of synthetic clotting factor.

We see gene therapy as a potential long-term solution for people with bleeding disorders… we would see this on a 10-year horizon as most likely being relevant to haemophilia B and then haemophilia A”  Spokesperson Haemophilia Society

“The results indicate that performing gene replacement therapy on a patient’s bone marrow cells can lead to production, storage and release of factor VIII from platelets directly at the site of an injured blood vessel to prevent uncontrolled bleeding for several years after treatment,” he told BBC News.

“This could greatly improve the quality of life for the nearly one in 10,000 individuals affected by this disorder, ultimately helping the patients to save a great deal of money in medical costs.”

The Haemophilia Society in the UK said it supported research into gene therapy.

In 2011, six patients with haemophilia B received gene therapy that allowed four of them to go without medication, raising hope for the future.

spokesperson said: “We see gene therapy as a potential long-term solution for people with bleeding disorders; given the practicalities and the research already done, we would see this on a 10-year horizon as most likely being relevant to haemophilia B and then haemophilia A.

“Nevertheless, we are mindful that no therapy can be used until it has passed every hurdle including clinical testing, and we are very mindful of the dangers of raising false hopes amongst those affected by the various bleeding disorder conditions.”

Other researchers have carried out gene therapy on dogs with haemophilia A using a different technique, which focuses on restoring clotting factor production in the liver.

The US researchers say this would not be applicable for all patients, such as those with liver damage.

They are applying for permission to carry out a clinical trial in the US within the next two years.

                    taken with kind permission  from

                       lesson prepared by Angloland skola |office(at)|

Words in the news

heamophilia –a genetic deficiency in clottingfactor VIII, which causes increased bleeding and usually affects males.

severe– serious, acute

symptom– signs of a disease or disorder

bleeding disorder – also called  coagulopathy  clotting disorderis  a condition in which the blood’s ability to clot is impaired. This condition can cause prolonged or excessive bleeding, which may occur spontaneously or following an injury or medical and dental procedures.

to affect –to have an influence on or effect a change in something

to account for – to be responsible for

deficiency – insufficiency, not being sufficient , lack, shortage

clotting –(coagulation,thrombogenesis) is the process by whichbloodformsclots so that the blood loss from a damaged vessel stops

to inherit genetically – to pass traits or characteristics from parents or ancestors to children

joint  the location at whichbonesconnect. They are constructed to allow movement (except for skull bones) and provide mechanical support, and are classified structurally and functionally

knee – the largest joint in the human body.The knee is a mobile trocho-ginglymus (a pivotal hinge joint), which permitsflexionandextension

ankle- ortalocrural region,is the region where thefootand thelegmeet

elbow –theelbow jointis thesynovialhinge joint[2]between thehumerusin theupper armand theradiusandulnain theforearmwhich allows the hand to be moved towards and away from the body

cure – medicine, remedy, medication

genetically engineered- the direct manipulation of an organism’sgenomeusingbiotechnology. NewDNAmay be inserted in the host genome by first isolating and copying the genetic material of interest usingmolecular cloningmethods to generate a DNA sequence, or by synthesizing the DNA, and then inserting this construct into the host organism.

error – mistake ,an act, assertion, or belief that unintentionally deviates from what is correct, right, or true.

genetic code –the sequence of nucleotides in DNA or RNA that determines the specific amino acid sequence in the synthesis of proteins. It is the biochemical basis of heredity 

platelets-small, disk shaped clear cell fragments (i.e. cells that do not have anucleus)which are derived from fragmentation of precursormegakaryocytes.  The average lifespan of a platelet is normally just 5 to 9 days. Platelets are a natural source ofgrowth factors. They circulate in thebloodofmammalsand are involved inhemostasis, leading to the formation ofblood clots.

repair-  to restore to sound condition after damage or injury; fix

internal bleeding(also calledinternalhemorrhage) is a loss ofbloodthat occurs from thevascular systeminto abodycavity or space.It can be a seriousmedical emergencydepending on bleeding rate and location of the bleeding (e.g. brain, stomach, lungs). It can potentially causedeathandcardiac arrestif proper medical treatment is not received quickly.

ultimately – eventually, finally, in the end

to improve – to make or become better  , to raise to a more desirable or more excellent quality or condition;

gene replacement theory –the use ofDNAas a pharmaceutical agent to treat disease. It derives its name from the idea that DNA can be used to supplement or altergeneswithin an individual’scellsas a therapy to treatdisease. The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene to replace amutatedgene

bone marrow – the flexibletissuein the interior ofbones. Inhumans,red blood cellsare produced in theheads of long bonesin a process known ashematopoiesis

storage –  a place where something is stored or placed and kept for later use

 to release – to free, to set free

site – place, position, location

blood vessel – a vessel in the human or animal body in whichbloodcirculates. The vessels that carry blood away from theheartare calledarteries, and their very small branches are arterioles.

to raise hope – to believe , trust with higher level of certainty

a spokesperson-someone engaged or elected to speak on behalf of others.

mindful –careful, attentive

hurdle – barrier, obstacle , hindrance

to restore to bring back to health

liver-the largestglandin the body, a spongy mass of wedge-shaped lobes that has many metabolic and secretory functions. The liver secretesbile, a digestive fluid;

applicable – a quality of being able to be applied, implemented, administered  

to carry out– to perform

a clinical trial –sets of tests inmedical researchanddrug developmentthat generate safety andefficacydata



taken with kind permission  from

                    lesson prepared by Angloland skola |office(at)|