Mevalonate kinase deficiency (MKD) represents a spectrum of clinical phenotypes that result from genetic variants in the
MVK
gene encoding mevalonate kinase. This spectrum ranges from the autoinflammatory disorder hyper‐IgD and periodic fever syndrome (HIDS) on the mild to the severe metabolic disorder mevalonic aciduria (MA). Homozygous variants in
MVK
lead to loss of enzyme function, and severity of clinical phenotype is linked to degree of residual enzyme activity. However, the disease has variable genotype/phenotype correlation, and additional modifier genes may exist to alter the clinical presentation. In addition,
MVK
variants have recently been associated with expanded phenotypes including retinitis pigmentosa, disseminated superficial actinic porokeratosis and inflammatory bowel disease. Further genetic and pathophysiological understanding of MKD is needed to better predict clinical course and direct management.
Key Concepts
MKD is a metabolic autoinflammatory disorder linked to variants in
MVK
, encoding mevalonate kinase.
MKD is an autosomal recessive condition with variants leading to loss of enzyme function.
Severely affected MKD patients have minimal mevalonate kinase activity and present with MA.
Patients with some residual enzyme activity lack metabolic and central nervous system features and manifest HIDS.
While there is significant genotype–phenotype association in MKD, there is a broad range of clinical features.
In addition, there are reports of asymptomatic patients despite biallelic variants and patients with heterozygous variants and HIDS.
There may exist modifier genes which impact the clinical features of MKD such as risk for complications including macrophage activation syndrome.
MVK variants have recently been linked to additional disorders including retinitis pigmentosa (RP) and disseminated superficial actinic porokeratosis (DSAP).
Further genetic and pathophysiologic understanding of MKD is needed to improve patient diagnosis and management.