Mevalonate kinase deficiency (MKD) is a condition that causes problems with the immune system.
People with MKD usually experience lifelong episodes of high fevers, joint and muscle pain, swollen lymph nodes, and stomach pain. These episodes can vary in how often and how severe they are, but on average, affected individuals have about twelve episodes each year. The number of episodes generally decreases as people age, but many still have at least six episodes a year by the time they turn twenty. The first episode usually occurs before the age of one. MKD can show up in two main forms: hyperimmunoglobulinemia D syndrome (HIDS) and mevalonic aciduria (MA). MA is usually much more severe than HIDS.
Hyperimmunoglobulinemia D syndrome (HIDS): HIDS is the most common form of MKD. People with HIDS typically have recurring fevers, joint and muscle pain, swollen lymph nodes, and a rash throughout their lives. Episodes usually happen every four to six weeks and can be triggered by illness, vaccinations, or injuries.
Mevalonic Acudria (MA): MA is a more severe form of MKD. Infants with MA may not grow and develop normally and might have intellectual and developmental disabilities. MA can also cause problems with the nervous system, like seizures, trouble coordinating movements (ataxia), and muscle weakness. Some people with MA may have eye problems and distinctive facial features.
Some individuals with MKD may develop a serious condition called macrophage activation syndrome (MAS). MAS causes very high fevers, low red blood cell levels, high iron levels in the blood, and organ problems. There is no cure for MKD, but treatments can help manage the symptoms.
MKD is caused by pathogenic (disease-causing) variants in the MVK gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance of having a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background.
Resources:
National Organization for Rare Disorders
Written August 2024
