MLIV is an autosomal recessive genetic disease, which means that it is genetically inherited through one’s parents, both of whom must be carriers of a defective gene, p19 which is responsible for MLIV. Mutated versions of that gene can be passed along to one’s children who become carriers of the mutation but who show no signs of the disease. In order for a child to be affected by MLIV, a child must receive a mutated copy of the gene from both the father and mother, as the diagram below shows. There is a 1 in 4 chance of having a child affected with MLIV when both parents carry the defective MLIV gene.