Neurofibromatosis: Tests and Diagnosis

What tests are used to diagnose neurofibromatosis (NF1)?

Many children are diagnosed with NF1 based on the presence of certain physical features. Criteria include the presence of at least six café-au-lait macules, freckling, ocular signs, presence of neurofibromas and plexiform neurofibromas, bone changes, or a diagnosis of NF1 in a relative. Individuals must have two or more of these characteristics to be diagnosed. Learn more about NFI symptoms and physical features.

An individual with NF1 is not always born with all the features of NF1. Many features develop over time. A genetic test for NF1 is also available when the diagnosis cannot be made based on a clinical exam. During a genetic test, a blood sample is taken, and a geneticist looks at DNA from the sample to determine if there is a change within one copy of the NF1 gene that prevents it from functioning properly.

Why choose Children’s Hospital Colorado for neurofibromatosis testing?

Our providers in our Neurofibromatosis Program have years of experience in diagnosing NF1. Because there are other medical conditions with similar features to NF1, we’re also very familiar with the signs of these alternative conditions and testing to distinguish between them.

Our laboratory staff are experts at caring for kids during blood draws. We use special topical creams to minimize the discomfort that may be experienced with a blood draw.

How soon can we expect testing results?

The genetic test for NF1 can take up to 8 weeks to receive results. This is the standard turnaround time for many genetic tests.

A positive test result means an individual has a gene mutation in the NF1 gene and will develop signs of NF1, although we cannot determine what signs will develop or when. About 5% of individuals with NF1 have a negative genetic test result, meaning we have not identified a gene change in the NF1 gene but they may later still develop signs of NF1. We follow and treat these patients as though they have NF1 until they are old enough that we feel more confident that they will not develop the condition.

How do providers at Children’s Hospital Colorado make a diagnosis?

The genetic blood test is routinely offered when NF1 cannot easily be diagnosed from a physical exam. The blood test is also offered to confirm a clinical diagnosis, for family planning and reproductive purposes, or to test other relatives who may be at risk of developing NF1.