Freebase(0.00 / 0 votes)Rate this definition: Arbol is a programming language which has been primarily developed for use in Genetic Programming experiments. It is a functional programming language inspired by the ideas of other small and esoteric languages.
Causes. In most cases of colon or rectal cancers, the cause or causes are unknown. Defects in genes that normally protect against cancer play the major role in causing polyp cells to continuously change and become cancerous.
Causes of PNH. PNH happens because of a change (mutation) in the PIG-A gene of a single stem cell in your bone marrow. This gene controls the creation of substance that helps certain proteins to stick to blood cells. Therefore, any blood cells created by this mutant bone marrow stem cell are abnormal.