Le déficit en mévalonate kinase en 2016

Mevalonate kinase deficiency is a rare, autosomal recessive, auto-inflammatory disease. This results from mutations in the gene MVK coding for the enzyme mevalonate kinase. This enzyme is involved in cholesterol and isoprenoids synthesis. Depending partially of the residual activity of the mevalonate kinase, the clinical spectrum realizes a continuum which extends from the mild phenotype of the hyperimmunoglobulinemia D and periodic fever syndrome (HIDS) to a lethal form of mevalonic aciduria. The HIDS is characterized by recurrent episodes of fever with an intense inflammatory syndrome, accompanied with lymphadenopathy, abdominal pain, diarrhea, arthralgia, hepatomegaly, splenomegaly and skin rash. The first attack more frequently takes place in the first year of life, even during the neonatal period, where it can be confused with a maternofetal infection. There is furthermore in mevalonate aciduria a psychomotor retardation, a failure to thrive, a cerebellar ataxia, a dysmorphic syndrome and a reduction of the visual acuity. The diagnosis is based on the mevalonic aciduria during febrile attack. Genetics confirm the diagnosis in more than 80 % of the cases. The dosage of IgD, low sensitive and specific, has no interest. There is no reference treatment. The less severe forms can be treated by non-steroidal anti-inflammatory drugs or steroids during febrile attacks. The most severe patients can be treated by biotherapy: antagonists of IL-1, TNF-α and IL-6.