Astounded by the huge response to my controversial article last week, I feel compelled to write about Gaucher disease, to clarify how genetic disorders are passed on, which I hope will answer many comments that were made. There were pertinent facts I was unable to write about due to restraints of article length. Most have not heard of Gaucher, and even in medical schools, student doctors are provided a meagre couple of paragraphs, explaining the nature of this rare illness. In reality, (as with any rare disease) few family doctors have patients with Gaucher. I am fortunate enough to be under the care of the world's leading specialist, a Professor who has dedicated his life's work to Gaucher disease.
Gaucher disease is named after the French doctor Philippe Gaucher who first described it in 1882 from observations of one of his patients. The disease has since been divided into three major types: but for now I will concentrate on the most prevalent: "Type 1" which is what I suffer from. Many patients are virtually asymptomatic and diagnosed incidentally because of prenatal or other genetic screening. The symptoms may begin early in life or later in adulthood, and include enlarged liver and spleen, Osteopenia (low bone mineral density) symptomatic skeletal features such as "bone crises" (episodes of chronic bone pain), osteonecrosis (bony destruction) of joints, and pathological fractures (not caused by trauma), diseased bone marrow, along with great fatigue, anaemia, risk of infection and bleeding.
Gaucher Disease is the result of a hereditary deficiency in the activity of one of the lysosomal enzymes required for breaking down particular particles in blood cells which are then unable to be eliminated. The absence of the enzyme (β-glucocerebrosidase) results in accumulation of glucocerebroside; which turn into Gaucher cells being stored in various organs.
Gaucher disease is inherited as an autosomal recessive disorder: this means that an individual must have two defective copies ("mutations") of the relevant gene, one inherited from the mother and one from the father. It takes two to tango and it also takes two parents both with the Gaucher gene to create a child with Gaucher disease. Both parents must be carriers in order for a child to be affected. If both parents are carriers, there is a one in four, or 25%, chance with each pregnancy for an affected child.
In my previous article I was remiss in mentioning that my husband was screened and thankfully found to be clear of the Gaucher gene, therefore our daughter is a normal healthy young woman who will never suffer from Gaucher disease. Genetic counselling and testing is recommended for families who may be carriers of the Gaucher gene. It is important to identify carriers within family members of the affected individual. Carriers have a single mutated gene and therefore will not suffer from Gaucher disease. Nonetheless, when planning a family, carrier status is important if the partner also carries a mutation.
The availability of enzyme replacement therapy (ERT) has revolutionized the status of Gaucher disease because it is deemed both safe and very effective. An international registry (ICGG; sponsored by Genzyme Corporation) has monitored the responses of thousands of patients world-wide for many years. Decreased spleen and liver volumes, increased haemoglobin levels and platelet counts usually occur within 6 months. The medication is administered by infusion bi-weekly and is according to body weight. Platelet counts in patients with extremely enlarged spleens may require longer periods to respond, but dramatic improvements continue within the first 2-4 years of therapy. Thereafter, regardless of dosage, responsiveness of all major disease features and markers plateau, and most patients achieve stabilization even while continuing therapy on the same regimen. The response of bones lags behind somewhat, but there is slight improvement over time.
I hope you now understand a little more about Gaucher disease. I would like to thank Professor Ari Zimran for help in verifying the medical information in this article. I am not a doctor, but merely a patient sharing my experiences with you. My aim is to offer support to fellow sufferers and caregivers, whether it be Gaucher disease or Parkinson's. Thank you again everyone for your comments last week which prompted much debate about a sensitive issue. Lively discussions are a good thing, making people stop and think, giving opportunity to voice different opinions, creating a chance to educate and bringing greater public awareness to important topics.