Inherited ichthyosis is caused by mutations, or changes, to genes.
Genes are codes that tell your body to make proteins, which determine how your body looks and works.
Ichthyosis gene mutations affect proteins that protect your skin and keep it moist. They also affect how quickly skin cells multiply or are shed.
Sometimes children whose parents don't have ichthyosis get the disease before birth. Some people have the gene mutation but don't show symptoms.