Gaucher Disease - What it is and what it means
Gaucher Disease is an autosomal inherited disorder. Because it is inherited, the disease will be present from birth but depending on the severity of the disease it may manifest in early childhood or only late into adulthood.
There are essentially three types of Gaucher Disease with type 1 or the non- neuronopathic form being the most common. Type 2 and 3 are designated as such because of neurological involvement.
There is a chromosomal abnormality and the only way the disease can be transmitted to a child is by him inheriting the abnormal gene from each parent. All people are born with a duplicate set of genes. One is inherited from the mother and the other from the father. If one of these genes is faulty, its function can still be maintained by other matching gene. If both are faulty, then the patient will show evidence of the defect. Therefore, in the recessive gene disorders the patient must have acquired the defective gene from both parents. Now, unless there is any suspicion, the parents will not know that they carry the bad gene because they are clinically normal. They will not show any manifestations of the disease as the good gene that they have will compensate for the bad gene.
The carrier rate for the defective gene is 1 in 20 in the Ashkenazi population. Gaucher Disease is more common in the Ashkenazi population and accounts for about 90 per cent f the American patients. In South Africa this is not completely true and it is in fact pan- ethnic with English, Afrikaner and black patients being diagnosed with increasing frequency. Worldwide there are in fact more non- Jewish patients with Gaucher Disease.
Gaucher Disease falls into the category of lysosomal storage disorders. These are a very rare group of disease but Gaucher Disease is the most common one in the group. There are about 50 identified patients in South Africa. Because of the genetic abnormality, the patient is born with a missing or defective enzyme called glucocerebrosidase.
Glucocerebrosidase is necessary to break down and allow for excretion of the naturally occurring waste product in the body called glucocerebrosidaside. In the absence of glucocerebrosidase, this product cannot be broken down and excreted and is now stored in various parts of the body.
The favoured storage sites are the spleen, liver and bones it is this accumulation that gives rise to the manifestation of Gaucher Disease. The spleen enlarges and shows its presence by abnormal distention. The spleen also becomes overactive and causes various blood abnormalities, notably anaemia, a low platelet count and a low white cell count. The bones become fragile and are subject to spontaneous fractures, and the liver also enlarges.
In types 2 and 3 Gaucher Disease there is deposition of the material in the brain which in turn causes varying degrees of neurological dysfunction.
The diagnosis of Gaucher Disease can be challenging but the test for the disease is relatively simple and inexpensive. The major problem encountered is one of late or of missed diagnosis. This problem is not unique to South Africa and patients will present to the doctor with a clinical picture which can be not dissimilar to other conditions, notably leukaemia, lymphomas, multiple myeloma, arthritis, various viral disease and bacterial infections.
Because of the rarity of the disease, Gaucher Disease is often not thought of often and often missed or misdiagnosed. In addition, because of the pan-ethnicity of Gaucher Disease, being non- Jewish is not a reason to exclude the diagnosis of Gaucher Disease.
The presence of enlarged spleen, bone pain or broken bones, anaemia or tendency to bleed and fatigue should alert the patient and the doctor to the possibility of Gaucher Disease. There is no arm of ever asking your doctor Could I have Gaucher Disease?"
Gaucher Disease can have a variable progression. In its more severe forms it will affect quality of life and can be incapacitating.
The diagnosis is a simple blood test where we look for the amount of glucocerebrosidase enzyme present in the patient. This can be done at any age. We are also able to the test for and identify carriers. This is important for family, and ante-natal counseling. It is important to realize that Gaucher Disease is an eminently treatable disease. There is now very specific and effective, and safe therapy for Gaucher Disease. The sufferings, pain and impaired quality of life can be overcome.
Essentially, the patient is infused with the missing enzyme. This in turn causes excretion of the accumulated substrate with ultimate normalization of the blood, bone abnormalities and shrinkage of the spleen.
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