Neurofibromatosis Type 1

What are the features of NF1 and how is it diagnosed?

NF1 is generally diagnosed through a physical examination by a doctor with experience in managing NF1, who will assess if the clinical diagnostic criteria of NF1 is met.

Although NF1 is a hereditary condition that one is born with, some symptoms develop gradually over a number of years. The severity of symptoms varies from person to person. Almost all individuals with NF1 are diagnosed by adulthood.

People may be diagnosed with NF1 by their doctors when they meet two or more of the following features:

1) 6 or more café-au-lait spots

• Multiple flat, coffee-coloured patches on the skin
• These spots must be more than 5 mm in diameter in young children and more than 15 mm in diameter after puberty
• About 10-25% of the general population has café-au-lait spots

2) Freckling around the armpits or groin

3) 2 or more neurofibromas or 1 plexiform neurofibroma

• Neurofibromas are pea-sized bumps that can grow on the nerve tissue or under the skin. They may appear just before puberty and tend to increase in number throughout life. The number of neurofibromas in individuals with NF1 can vary greatly, from just a few to hundreds.
• Plexiform neurofibromasare larger and deeper tumours around the nerves. Sometimes, they cannot be seen or felt, and may be present from early childhood. They usually do not cause problems, but a few may grow quite large and cause local effects or develop into cancer.

4) Optic pathway glioma

• A tumour along the main nerve of the eye that is responsible for sight
• Occurs in 15-20% of children with NF1

5) 2 or more Lisch nodules

• The appearance of tiny tan clumps of pigment within the iris of the eyes, that do not affect vision

6) Specific skeletal changes

• The enlargement or malformation of bones in the skeletal system such as tibial dysplasia (curved lower leg bone) or sphenoid dysplasia (abnormally shaped bone around the eye)

7) Family history

• A parent, sibling (brother or sister), or child with NF1

8) A fault (i.e., mutation) in the NF1 gene

Some children under 8 years of age may have café-au-lait spots, but no other signs of NF1. These children should be monitored carefully to see if other signs of the condition develop

Other medical concerns related to NF1

The following problems are more common in individuals with NF1 and need to be watched for and treated if necessary:

• Learning difficulties
• Attention deficit disorder (ADD/ADHD)
• Larger head size than average
• Shorter stature/height than average
• Scoliosis (curvature of the spine)
• Early puberty
• High blood pressure
• Headaches
• Increased risk of cancer

The features of NF1 can be very different even among members of the same family.

Most people with NF1 do not have many of the health problems listed above, and live long, healthy lives.