Neurofibromatosis is the general name for a number of genetic conditions that cause tumours to grow along your nerves.
Tumours are swellings formed by a growth of cells. In neurofibromatosis, the tumours are usually non-cancerous (benign).
Neurofibromatosis type 1 (NF1) is the most common type, affecting about one in 3,000 births.
Neurofibromatosis type 2 (NF2), which is much less common, has different symptoms and is caused by changes in different genes, so is covered separately.