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Behind the brown spots: What exactly is neurofibromatosis type 1?
Neurofibromas are a group of genetic disorders involving the nervous system in which tumors grow in the nervous system. These tumors are generally benign and usually involve the skin or surrounding bone. Although symptoms are often mild, each disease manifests itself differently. Among them, neurofibromatosis type 1 (NF1) is characterized by brown spots, neurofibromas, scoliosis, and headaches; while neurofibromatosis type 2 (NF2) may cause early hearing loss, cataracts, tinnitus, and difficulty walking. Or symptoms such as difficulty in balance and muscle atrophy.
In the United States, approximately one in 3,500 people has NF1 and one in 25,000 has NF2.
All three types of neurofibromas are caused by mutations in certain tumor suppressor genes and may be inherited, with about half of cases occurring spontaneously during early development. Different mutations lead to the development of three different types of neurofibromas. Tumors in NF1 are primarily neurofibromas, which are tumors of the peripheral nerves; tumors of Schwann cells are more common in NF2 and neurofibromatous-type tumors.
Signs and symptoms
Neurofibromatosis type 1 (NF1) may cause learning and behavioral problems in the early stages, and about 60% of children with the disease show mild difficulties in school. Characteristic symptoms of NF1 include:
- Six or more brown skin spots
- At least two neurofibromas
- At least two corneal tumors
- Abnormal growth of the spine (scoliosis)
- Lisch nodule
- Adrenal gland tumors
The most characteristic symptom of neurofibromatosis type 2 (NF2) is hearing loss, which is caused by the tumor compressing the auditory nerve.
Cause
Different types of neurofibromas are caused by different genetic mutations. The NF1 gene is located on chromosome 17, and NF2 is located on chromosome 22. These are dominant inheritances, so if one parent has neurofibromatosis, their children have a 50% chance of inheriting the disease. Regardless of the severity of a parent's condition, a child's condition may differ.
Pathophysiology
NF1 is the most common of the three types and is mainly caused by mutations in the NF1 gene. The function of this gene is to inhibit the formation of tumors. Mutations in NF1 cause the growth of neurofibromas. Relative to NF2, genetic mutations in NF2 can lead to the loss of function of another protein called merlin, which can lead to the formation of tumors.
Diagnosis
Neurofibromatosis is usually diagnosed based on symptoms, examination, medical imaging, and biopsy. Genetic testing is sometimes used to aid diagnosis.
Treatment
While there is no known prevention or cure, surgical removal of the tumor is an optional treatment. The risks of surgery need to be carefully assessed, especially in children. Sometimes chemotherapy may be used for other complications.
Prognosis
For most patients with NF1, symptoms are usually mild, and patients' life expectancy is comparable to normal people. However, symptoms of NF2 may not be apparent in adulthood but increase the risk of early death.
History
Descriptions of neurofibroma date back to the 1st century. In 1882, Friedrich Daniel von Recklinghausen formally described the disease, and it was named after him.
What is the impact of neurofibromatosis? Can people find better ways to support and manage these symptoms as they impact their lives?
