On 11/16/12 one of my best friends passed away from a very rare disease known as Hemophagocytic Lymphohistiocytosis, or HLH. The exact cause of HLH is unknown. It is a disorder of the immune system, it leads to the activation of infection fighting cells called histiocytes and lymphocytes. Normally they are supposed to travel throughout the body and destroy foreign material and fight infections. Patients with this disease have too many of these activated histiocytes and they begin to accumulate in normal tissue and cause inflammation and damage to a variety of organs. The most common sites of involvement include the bone marrow, lymph nodes, liver, spleen, and brain. (“Hemophagocytic Lymphohistiocytosis” 1.) There are two forms of this disease, the familial or primary form, and the acquired or secondary form (Anaesth 1.). The primary form of Hemophagocytic Lymphohistiocytosis is a genetic disorder. About one in every 200,000 children is diagnosed with Familial HLH. In most cases around 70-80%, develop symptoms before the age of 1 and approximately 10%, experience symptoms within the first 4 weeks of life. In the same family, children with familial HLH usually develop symptoms around the same age.
FHLH can be inherited in either an autosomal recessive manner or in an x-linked manner. (What is HLH? 1.) The autosomal recessive manner takes place when the child has two copies of the abnormal gene, one from each parent. In the x-linked case, the mother passed an abnormal x chromosome to her son. FHLH is accountable for only 25% of all HLH cases. (“questions and answers” 1.) If two carriers of this disease mate there will be a 25% chance that their child will have HLH by the time its 2 years of age. To date there are only 9 genetic causes of the primary form that have been discovered, which is only about 50% of all childhood cases in the United States. (What is HLH? 1.) The acquired or secondary form of develops abnormal activation...
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