Secretion both DNA and proteins. It was discovered in "Agrobacterium tumefaciens", which uses this system to introduce the T-DNA portion of the Ti plasmid into the plant host, which in turn causes the affected area to develop into a crown gall (tumor). "Helicobacter pylori" uses a type IV secretion system to deliver CagA into gastric epithelial cells, which is associated with gastric carcinogenesis. "Bordetella pertussis", the causative agent of whooping cough, secretes the pertussis toxin partly through the type IV system. "Legionella pneumophila", the causing agent of legionellosis (Legionnaires' disease) utilizes a type IVB secretion system, known as the icm/dot (intracellular
Meleda disease Meleda disease Meleda disease (MDM) or "mal de Meleda", also called Mljet disease, keratosis palmoplantaris and transgradiens of Siemens, (also known as "acral keratoderma", "mutilating palmoplantar keratoderma of the Gamborg-Nielsen type", "palmoplantar ectodermal dysplasia type VIII", and "palmoplantar keratoderma of the Norrbotten type") is an extremely rare autosomal recessive congenital skin disorder in which dry, thick patches of skin develop on the soles of the hands and feet, a condition known as palmoplantar hyperkeratosis. MDM is most common on the Dalmatian island of Mljet (or "Meleda"), thought to be because of a founder effect. It is of autosomal recessive inheritance.