Mevalonate Kinase Deficiency (MKD / HIDS)

What do MKD and HIDS mean?

Mevalonate kinase deficiency (MKD) is associated with disease-causing variants in both copies of MVK, the gene for the mevalonate kinase enzyme. MKD is the disease; MVK is the gene.

The milder end of the spectrum was often called hyperimmunoglobulinemia D syndrome, or HIDS. The more severe end has been called mevalonic aciduria. The spectrum can include effects on growth and development as well as inflammation.

What can episodes look like?

Episodes often start in infancy or early childhood. Fever may occur with swollen lymph nodes, abdominal pain, vomiting or diarrhea, mouth ulcers, rash, and muscle or joint pain. Episodes commonly last several days. Infections, stress and vaccinations can sometimes precede a flare; this does not mean routine vaccines should be avoided. Discuss an individual vaccination plan with the care team.

How is it evaluated?

Diagnosis draws on the history, examination and genetic testing, sometimes with biochemical testing such as urine mevalonic acid. A high IgD level alone does not establish MKD, and a normal level does not rule it out. A genetic specialist can explain inheritance, carrier status and implications for relatives.

Treatment and life between episodes

Specialists may use IL-1–blocking therapy to control inflammation. The plan depends on severity, episode frequency and inflammation between attacks. Supportive care, growth and development, medication safety, and the family’s daily experience also matter. A treatment plan should cover both prevention and what to do during illness.

• What should we record during an episode?
• Which tests are useful during a flare and when well?
• How will treatment affect vaccines or an ordinary infection?
• What support is available for missed school or work?

A symptom diary can make the pattern easier to discuss. Seek prompt advice for dehydration, unusual lethargy, breathing difficulty or symptoms that differ substantially from the established pattern.