Neurofibromatosis (commonly abbreviated NF; neurofibromatosis type 1 is also known as von Recklinghausen disease) is a genetically-inherited disorder in which the nerve tissue grows tumors (neurofibromas) that may be benign or may cause serious damage by compressing nerves and other tissues. The disorder affects all neural crest cells (Schwann cells, melanocytes and endoneurial fibroblasts). Cellular elements from these cell types proliferate excessively throughout the body, forming tumors; melanocytes also function abnormally in this disease, resulting in disordered skin pigmentation and café au lait spots. The tumors may cause bumps under the skin, colored spots, skeletal problems, pressure on spinal nerve roots, and other neurological problems.