The following information may help to address your question:
What is hyper IgD syndrome?
Hyper IgD syndrome is the less severe form of a
metabolic disorder known as
mevalonate kinase deficiency. It is considered an auto-inflammatory disease, with
recurrent episodic or chronic unexplained inflammation, characterized by periodic episodes of fever, and other symptoms such as joint pain, swollen
lymph nodes, skin rash, headaches, and abdominal pain. Most episodes last several days and occur periodically throughout life. The frequency of episodes and their severity vary greatly from person to person.
[1][2] These attacks can occur spontaneously or be triggered by vaccinations, infections, and/or emotional or physical stress. Growth and development is usually not affected. Hyper IgD syndrome is caused by
mutations in the
MVK gene which provides instructions for making the mevalonate kinase
enzyme. The mutations result in the partial deficiency of the enzyme. A more severe form of maevalonate kinase deficiency is known as
mevalonic aciduria.
[3][4] It is
inherited in an
autosomal recessive manner.
[1][4] Treatment is with
anakinra, and other medications,
but not all patients show a complete response. In most cases, the frequency of the disease's episodes decreases over time.[2]
Last updated: 6/26/2017
What are the signs and symptoms of hyper IgD syndrome?
Hyper IgD syndrome is characterized by periodic high fevers that may be associated with other symptoms including:
[3][5][2]
Most episodes last several days and occur periodically throughout life.
[1] The frequency of episodes and their severity vary greatly from person to person.
[1][3] The first attack usually takes place during infancy.
[5] Patients may have no symptoms between attacks. However, in some patients, the attacks may be so frequent that the symptoms persist.
[3] The attacks can occur spontaneously or be triggered by vaccinations, infections, and/or emotional or physical stress. Growth and development is usually not affected.
[5][1] Disease complications sometimes seen in adults include
amyloidosis, abdominal
adhesions, and very rarely joint
contractures.
[5]
Some people seem to have an intermediate form that is more severe than hyper IgD syndrome but less severe than classic mevalonate aciduria. These people suffer from a neurological illness with or without periodic fever.
[2]
Last updated: 6/26/2017
What causes hyper IgD syndrome?
Hyper IgD syndrome is caused by mutations in the gene
MVK which
encodes the enzyme mevalonate kinase. The mutations lead to a partial deficiency of the enzyme mevalonate kinase.
[3][5] This enzyme converts a substance called mevalonic acid into mevalonate-5-phosphate. This conversion is the second step in a
pathway that makes cholesterol. The cholesterol is later converted into steroid
hormones and bile acids. Steroid hormones are needed for normal development and reproduction, and bile acids are used to digest fats. The enzyme also helps to produce other substances that are necessary for certain cellular functions, such as
cell growth, cell maturation (differentiation), formation of the cell's structural framework (the cytoskeleton), gene activity (expression), and
protein production and modification. A role for this pathway in inflammation is still not completely understood, but it is known that the mevalonate pathway produces cholesterol, and also some compounds which are necessary for the proper interaction and function of these proteins.
[6]
Last updated: 6/26/2017
Is hyper IgD syndrome inherited?
Hyper IgD syndrome is inherited in an
autosomal recessive manner, which means both copies of the gene in each cell have mutations. The parents of a person with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
[1][5]
Last updated: 6/27/2017
How might hyper IgD syndrome be treated?
The mainstay of the treatment of hyper IgD is anakinra, but not all patients show a complete response. Usually five to seven daily injections are sufficient to prevent an early relapse. Anakinra can also be used to prevent vaccine-induced attacks in patients that need immunizations.
[6]
In 2015, a group of experts from different countries proposed recommendations for the management of several anti-inflammatory diseases including hyper IgD syndrome. Recommendations include:[7]
- NSAIDs may provide symptom relief during inflammatory attacks
- Short-term glucocorticoids, with or without NSAIDs, may be effective for alleviating inflammatory attacks
- Short-term IL-1 blocking agents (anakinra or canakinumab) may be effective for ending inflammatory attacks and should be considered to limit or prevent steroid side effects or as a maintenance therapy
- If one IL-1-blocking agent at an adequate dose is ineffective or not well tolerated, a switch to another IL-1-blocking agent or another biological agent (including TNF-α blockers (etanercept (Enbrel), rituximab, o infliximab) or IL-6 blockade (tocilizumab) should be considered.
- If TNF-α blocker is ineffective or intolerable, a switch to another biological agent (including an IL-1- or IL-6-blocking agent) should be considered.
In selected cases with severe disease that does not improve, and poor quality of life, referral to a specialist center for consideration of allogeneic hematopoietic stem cell transplantation is recommended.[7]
Consultations with the following specialists may be helpful: dermatologist, rheumatologist, and infectious disease specialist (to evaluate periodic fever).[3]
Last updated: 6/26/2017
What is the prognosis for individuals with hyper IgD syndrome?
Life expectancy is not shortened except for in rare cases where severe infections or kidney
amyloidosis occur. Between fever attacks, patients are generally free of symptoms. Attacks do continue throughout the lifetime, although there may be a slight decrease following adolescence.
[3] A long-term follow-up study showed that the frequency of the attacks decreases over time, but about half of the patients more than 20 years of age still experience six or more attacks per year, with quite an impact on quality of life.[6]
Last updated: 6/26/2017
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