The root cause of Muckle-Wells Syndrome is the mutation in gene CIAS1. This gene is responsible for protein cryopyrin. Because of the mutation, excess amount of the protein cryopyrin is produced. This protein is responsible for regulation of another protein called interleukin which is responsible for inflammation. An increase in interleukin results in increased inflammatory response causing the characteristic features like fever, joint pain, and rashes .
MWS is an autosomal dominant pattern of inheritance meaning that one copy of the defective gene from either parent is enough for a child to develop Muckle-Wells.