<s>[INST] <<SYS>> This is a medical question of type : causes <</SYS>> What causes Hyper-IgD syndrome ? [/INST] What causes hyper IgD syndrome? Hyper IgD syndrome is caused by mutations in the gene encoding the enzyme mevalonate kinase (MVK). The mutations lead to a decrease in the enzymatic activity of the gene. The gene is located at chromosome 12q24. </s>