Congenital skin laxity is caused by mutations in genes related to elastic fibres, which exist not only in the skin but also in muscles, tendons and blood vessels. If the elastic fibres throughout the body are diseased, not only is there skin laxity, but other tissues and organs can also be affected to varying degrees, such as abdominal muscle laxity and pectoral muscle laxity. If the abdominal wall muscles are too lax, the abdominal organs will tend to protrude outwards under the skin, forming a hernia.