The development of noncancerous tumours along nerve fibres
- Present at birth
- Due to an abnormal gene often inherited from one parent
- Gender and lifestyle are not significant factors
Neurofibromatosis is a genetic disorder that causes numerous soft, noncancerous growths, known as neurofibromas, to appear throughout the body. These tumours grow from nerve tissue and develop along nerve pathways. If the condition is severe, it can be disfiguring and may be distressing for the affected child and his or her family.
There are two types of neurofibromatosis. The more common of the two, known as neurofibromatosis 1, affects about 1 in every 2,500 babies born in the UK. The other type, neurofibromatosis 2, is extremely rare, and the symptoms do not usually appear until adulthood. Both types are caused by an abnormal gene that is inherited in an autosomal dominant manner (see Gene disorders). The abnormal gene for neurofibromatosis 1 is located on chromosome 17, and the gene for neurofibromatosis 2 is located on chromosome 22.
What are the symptoms?
The symptoms of neurofibromatosis 1 usually appear during early childhood. They may include:
Numerous pale-brown, flat patches with irregular edges, known as café au lait spots, that develop on the skin.
Soft growths under the skin, which can range in size from hardly noticeable to large and disfiguring.
Freckles in the armpit and groin areas.
Adults with neurofibromatosis 2 tend to develop tumours in the inner ear, which can affect hearing, but they rarely have tumours on the skin.
Are there complications?
Complications may occur when growing tumours press on the surrounding organs or nerves. For example, vision may be affected if a tumour develops on the optic nerve, which connects the eye to the brain. Tumours can also cause curvature of the spine (see Scoliosis). Other possible complications include high blood pressure (see Hypertension), epilepsy, and learning difficulties. In rare cases, the tumours become cancerous.
What might be done?
Neurofibromatosis 1 is normally diagnosed in childhood when the symptoms appear. Neurofibromatosis 2 is usually diagnosed in adulthood. The doctor will arrange for CT scanning or MRI of the brain to look for tumours, and hearing and vision may be tested.
There is no cure for the disease, and its progression cannot be slowed. Many cases are mild, but long-term care may be needed for severely affected children. Tumours that are large, painful, or disfiguring can often be surgically removed. Complications are usually treated as they arise. For example, a child with learning problems may need special education. Parents of an affected child who want to have more children may be offered genetic counselling.
In mild cases of neurofibromatosis, life expectancy is normal, but, if tumours are extensive and cancer develops as a complication, lifespan may be reduced.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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