|Mevalonate Kinase Deficiency (MKD) also known as Hyper IgD Syndrome (HIDS)|
MKD (HIDS) is an inherited auto inflammatory disease that is caused by an inherited autosomal recessive gene mutation of the mevalonate kinase gene (MVK), from both parents.
Classic HIDS is caused by the inherited MVK gene mutation. Clinical symptoms of HIDS, along with continuously high IgD values (more than 100 IU per milliliter) on 2-IgD lab tests done one month apart lead to the diagnosis of Classic HIDS in most patients. Over 80% of HIDS patients also have high IgA levels along with high IgD levels. During an attack, leukocytosis, high levels of C-reactive protein (CRP) and serum amyloid A are noted. Mevalonate aciduria is also noted in many cases.
The MVK gene mutation is uncommon, but in The Netherlands, 1:350 people carry the recessive gene mutation. Two parents have to carry the recessive gene mutation to lead to the autosomal recessive inheritance of HIDS symptoms in a child. Most HIDS patients are Caucasian, live in western European countries and 60 percent are either Dutch or French.
Symptoms of HIDS are noted by the first year of life in most patients. Bouts of HIDS symptoms or attacks usually begin with chills, then a quick rise in temperature that causes a fever for 3-7 days. HIDS patients may have a diffuse erythematous maculpapular rash, urticaria, headaches, joint pain, large joint arthritis, enlarged cervical lymph nodes, vomiting and diarrhea during the flares. Some patients have petechiae or purpura, and even painful aphthous mouth or vaginal ulcers.
The intensity of symptoms begins to taper off after a few days. The attacks can occur with great frequency, often every two to six weeks, and are often triggered by vaccinations, minor trauma, stress, surgery or unknown causes.
Hyper IgD Syndrome (HIDS) presents with longer episodes of flare-ups than CAPS, and a different rash. Once the attack is over, patients are free of symptoms, but it may take awhile for the joint pain and skin rash to fully disappear. Patients can have attacks off and on throughout their life, and patients can sometimes be free of symptoms for many months or even years in some cases. Generally, patients have the greatest frequency of HIDS attacks during childhood through adolescence. Amyloidosis is not seen in HIDS.
Most cases of HIDS cause IgD levels to be elevated during attacks of symptoms. CAPS and many other Periodic Fever Syndromes are not commonly associated with elevated IgD levels.
For more information on HIDS, go to http://www.hids.net