Everything About Fucosidosis - A Rare Disorder
Fucosidosis is rare lysosomal storage disorder derived from the oligosaccharide family of diseases. It is created by autosomal recessive mutation of the (FUCA 1) gene which causes a deficiency of the enzyme alpha-L-fucosidase in the body. This inhibits the ability to break down fucose thus presenting major disorders in the body as it is a vital sugar that needs to be synthesis in the body. Fucosidosis was found to effect lysosomal pathways as lysosomes contain hydrolytic enzymes that aid with the degradation of biomolecules such as cytoplasmic material and organelles. As the body is deficient in alpha-L-fucosidase, proteins in the lysosome such as glycoside (carries and delivers catabolic products in the cytosol) are affected by blocking the catabolic chain from degradation and therefore causing accumulation of oligosaccharides in the lysosomes. This then leads to failures in the lysosomal pathway as it becomes blocked and overtime different diseases would begin to be expressed onto the individual.
In similar ways glycan degradation is also affected by fucosidosis. This is seen in two forms the most common being degradation of complex N-Glycans which is when the oligosaccharides begin to build up in the lysosomes due to the disturbance in the degrative enzyme therefore not allowing the synthesis of the products therefore causing a loss in the linkage to outer branches of the chain. This cause N-glycan to be intact and bound to asparagine which stops all function of the enzyme. The second pathway is the gradation of oligomannosyl N-Glycans is close to identical to the complex N-glycan expect beta-mannosidase is unable to complete the degradation process due to product accumulation. Fucosidosis effect vary for different individuals. Overall, it causes major effects to all cells in the body especially brain and liver cells as they are extremely sensitive to oligosaccharides.
This damage to the brain and liver cells leads to serve distortion on the body common example being neurological deterioration, skin and growth abnormalities, skeletal deformities, loss of muscle tone which overtime eventually leading to death depending on which type of disorder the patient possesses which are type I and type II. Type I is seen to be life threating due to is rapid progress from the early stages of the patients lives while type II is a milder and less server case of fucosidosis.
Fucosidosis is an inherited autosomal recessive trait. It needs to be carried by both parental genes for the offspring to possess 25% of the disorder. The chances of the offspring would increase if the parents are from immediate family. When this occurs, FUCA 1 genes would become mutated and unable to perform. The key enzyme which is affected by fucosidosis in the alpha-L-fucosidase. This enzyme is vital for catalysing chemical reactions by controlling the levels of oligosaccharides in the body by breaking them down using the glycan complex degradation pathway in order to be used by the body when necessary. This causes problems to occur within the cells and which in turn will affect the enzymes half-life as it stands on 7.2 to 20 minutes.
This changes the reaction time of the enzyme where it would not be able catalyse the products before it denatures. This then causes a decrease in the overall levels of the alpha-L-fucosidase enzyme. Due to insufficient enzymes, the oligosaccharides accumulate and cause blockage to the other receptors such as glycoside therefore stopping transport of important products to the rest of the body. This causes the body to start to become damaged which will affect the brain greatly. This causes activation of fucosidosis to slowly breakdown white matter of the brain which creates permanent damage to the body.
Research
Fucosidosis is a very rare disease, meaning very little research has been occurring to determine the cause of this disorder. Not only is it rare but it also varies for different individuals making it hard to develop a general thesis of how it may affect the body of the patients.
Many cases of children have been in use to determine to cause of such damage, but all display different reasons and different symptoms which contradicts the opposing case.What can understand from the studies was that in the case of the 8-month fetus and 8 years old girl was that the disorder affected them differently even though it was caused through the same medium as their parents were both carries due to them being immediate family. Passing on the mutation to their offspring, the disorder acted a similar way blocking the receptors from carrying or receiving information to then deliver to the brain.
In both these cases the oligosaccharides caused a built in which effected the glycoside therefore the brain was unable to access the essential sugars it needs to function. The lack of sugars caused the brain in both cases to degrade its white matter. As what can be determined by the studied the main signal is the brain as that is what is affected the most. Once the brain is affected all over organs also become affected which is what caused the abnormalities presented in the cases. This later on was seen as the both cases physical form changed as both suffered from skeletal disorders and neural damage, while the girl suffered from extreme swelling of the hands, feet and tongue.
The cases showed that even though the brain was the target for both studies, it presented different symptoms where the 8-month fetus was able to be cured through a bone marrow transplant while the 8 years old’s body rejected all treatment and was unable to respond. Fucosidosis does not have a general cure therefore therapeutic treatments are used to stabilise the patient’s symptoms from worsening. The therapeutic treatments include physiotherapy and hydrotherapy which aids to remove mucus build up in the chest. It is also used for general wellbeing in keeping the patients active and mobile to maintain the body function for as long as possible.
Another therapeutic treatment used is anaesthetics. Due to some patients suffering from major damage, they could face major painful episodes either through seizures or skeletal disorders. Therefore, a trained professional is allowed to administer the needed dosage for the patient if needed in order to stabilise their condition. This is done as there is no treatment that can reverse this disorder as the only treatment is to preserve the patients life for as long as possible.
Diagnosis
There are variety of tests to confirm the presence of fucosidosis in an individual. Usually a diagnosis for fucosidosis are mostly aimed for infants with skeletal disorders as of their first year in life. The most common way is through a urine test in which a sample is taken from the patient and test for increased levels of oligosaccharides. This is then followed by blood test or a skin biopsy where again a sample is taken and tested for decreased amounts of alpha-L-fucosidase in the patient to further prove the test. Other tests include electron microscopic examination of samples from skin, liver, lung, heart kidney etc to test and see if any lamellar bodies are present within these cells. Advanced magnetic resonance imaging and computer assisted tomography of the brain can confirm abnormalities within the white matter which can indicate the presence of fucosidosis.
In extreme cases, confirmation of fucosidosis and the depletion of alpha-L-fucosidase can do performed using enzyme assays by culturing fibroblast and leukocytes. This is a necessary test as some individuals may show results of low or depleted levels of alpha-L-fucosidosis when they may not have any history of the disorder when only testing the enzyme and plasma. Through testing the fibroblasts and leukocytes, more accurate results would be produced. This type of testing is called chronic villus sampling and can be done in the early stages of pregnancy the sample is taken from the surrounding fluid of the fetus to be tested and studied.
Treatment
For fucosidosis, there is currently no developed treatment that can stop or reverse this disorder which can be due to the large variety of different effect it can cause to different individuals therefore the medical clinics focus giving treatments to stabilise and manage the symptoms of each patient. An example being that patient are given antibiotics to treat respiratory infections which cloud be a consequence of fucosidosis.
In recent discovery, medical professional used haematopoietic stem cell transplant on newborn babies. These cells represent bone marrow cells which are found in the umbilical cord blood therefore are collected and then replaced with a healthy donors cells. This treatment was proven to work as follow with the patient displayed an improvement in response. Continuing from that research medical professional tested the same technique on an 8-month fetus in which a bone marrow transplant from a healthy fetus was used to introduce high levels (normal) of alpha-L-fucosidase in the body.
The results also showed promising advancements as the fetus was able to gain growth and have a normal skeletal form. This treatment was proven to be successful to this patient but for many others the treatment failed as they body either rejection the blood or the symptoms worsen. This breakthrough demonstrated that in some cases transplants can cure some individuals. This in turn could be very challenging as fucosidosis drastically varies from different patients and due to its rare form of 1 in 2million individuals possessing the disorder it proved to be very difficult in researching and testing ways to achieve a cure for all patients.
Scientists and researchers also are currently testing a new treatment that would be available very soon for the patient to use. This treatment is called ‘Gene Therapy’ and it works by placing the effected gene with a copy of a normal gene. This interaction would influence the faulty gene to act as a normal gene and thus increase alpha-L-fucosidase in the FUCA 1 gene. This could aim to be promising but there has not been much testing placed on its results.
Policy
Due to its rare nature, fucosidosis does not possess many polices or legislations put in place in most of the countries. Most disorders with similar effect to fucosidosis have similar policies that is placed under lysosomal storage disorder. Due to more awareness being drawn into such disorders, the state, federal and international governments have acted into putting in place treatments to aid in early detection with repaid prevention of worsening symptoms. After being introduced to fucosidosis in many parts of the world and seeing its effect on the patient WHO placed early screening programs in which were issued in 1968 where newborns and other young patients could use to receive an early detection on the disorder. This policy was then renewed in 2008 where the criteria was updated to suit the needs of the patients and to add the advancement that has occurred throughout the years for better detections. This was also released with preventative programs that educated individuals of ways to minimise the occurrence of fucosidosis. May other policies have been used since the discovery of fucosidosis.
A current aid from the international legislation demonstrated how the testing for any lysosomal storage disorder should be practiced by all medical and research professionals in 1968. This algorithm was created to accurately test and characterise patient with serve abnormalities occurring to their disorder to allow better diagnosis of their condition. This process is still in use today as it provides accurate results of the patients in accordance with their symptoms.
