What it is: NF1 is part of a group of genetic conditions called neurofibromatosis, said Associate Professor Joanne Ngeow, Senior Consultant at the Division of Medical Oncology, and the head of Cancer Genetics Service at the National Cancer Centre Singapore (NCCS).
As a whole, NF is a highly under-diagnosed condition in Singapore, said Assoc Prof Ngeow. Aside from NF1, the most common form, there are two other types of NF – NF2 and schwannomatosis.
Risk factors: Assoc Prof Ngeow said that about half of all NF cases inherit the condition from their parents, while the other half is a result of a spontaneous mutation of the NF1 or NF2 genes during conception. All individuals who have NF have a 50 per cent chance of passing it onto their children. It does not skip generations, and can affect both males and females from all ethnicities.
People with NF1 also have an increased risk of cancers, such as breast cancer and brain cancer.
Incidence rates in Singapore: NCCS’ Cancer Genetics Service currently manages about 30 families with NF1. “We expect the incidence rate of NF1 individuals to be 1:3000 in our local population, similar to that of other populations globally,” said Assoc Prof Ngeow.
Symptoms: Only a physician can make a formal diagnosis of NF1, and the patient must meet two or more of the following criteria:
- A family member with NF1.
- Six or more cafe-au-lait macules, which are skin pigmentation in the form of multiple flat, light brown spots on the skin.
- Freckling in the armpit or groin.
- Two or more neurofibroma tumours (benign nerve tumours that can grow on or under the skin) or one plexiform neurofibroma (a larger and deeper tumour around the nerves). “10 per cent of plexiform neurofibromas may become cancerous,” Assoc Prof Ngeow said.
- Optic pathway glioma, which is a tumour that grows along the optic nerve in the brain.
- Osseous lesion, a bony lesion, such as sphenoid dysplasia, an abnormal growth of the bone behind the eye.
- A faulty NF1 gene found by genetic testing.
“The severity of symptoms can range from extremely mild to severe, and can vary within individuals of the same family as well. There is no way to predict who will have a mild case or who will develop more serious symptoms, but the majority of individuals (60 per cent) usually experience minor symptoms,” said Assoc Prof Ngeow.
Screening, management and treatment: There is no cure for NF, she said, but the symptoms can be managed; and the sooner it’s done, the better the outcome.
“As NF1 can affect different parts of the body… doctors and healthcare professionals from different specialties may be involved in the care of NF1 patients, which may include dermatologists, neurologists, ophthalmologists, orthopaedists, oncologists, cardiologists and genetic counsellors,” said Assoc Prof Ngeow.
She added that anyone who has features suggestive of NF should consider further assessment with a genetics service. You can ask your primary doctor for a referral for genetic counselling, to confirm the presence of a genetic condition within the family, if any. It usually involves a one-time blood test.
Depending on the symptoms and signs associated with NF1, screening and treatment include annual physical and eye examinations, the option of surgically removing benign nerve tumours and surveillance for children with a type of skin lesion called xanthogranulomas.