Mevalonate Kinase Deficiency (MKD)/Hyperimmunoglobulin D With Periodic Fever Syndrome (HIDS) (OMIM #260920) is a rare autosomal recessive SAID characterised by bi-allelic mutations in the mevalonate kinase (MVK) gene (12q24.11) resulting in defective cholesterol biosynthesis and increased urinary excretion of mevalonic acid (53). Here, MVK is linked to mevalonic aciduria.