MicroRNAs are small molecules which have recently been discovered in cells. They are known to be responsible for the normal development of cells and when they are disrupted can contribute to the development of cancer. Many previous studies have been done evaluating the expression of microRNAs in normal tissues as well as in a wide variety of cancers.

Recently, microRNAs from tumor cells have been detected circulating in the blood of patients with cancer. This presents a novel opportunity to assess the utility of microRNAs in the blood as an early predictor of cancer as well as a marker of response to therapy. No previous studies have been performed evaluating microRNAs in archived tumor tissue and blood of patients with Neurofibromatosis type 1 (NF-1). The investigators propose a feasibility study to evaluate the presence of microRNAs in archived tumor tissue and the blood of patients with NF-1. If the investigators are able to identify circulating microRNAs in this population of pediatric patients, they will build upon this data in proposing a future study.

Inclusion Criteria:

• Patients ages 2 years to 21 years.
• Patients with NF-1 being followed in the Neurofibromatosis Clinic.
• Patients have had MRI imaging in the 24 months prior to enrollment on the study.
• Patients may have known concurrent malignancies such as plexiform neurofibroma.
• Patients and/or parents/legal guardians must have signed an informed consent and assent when applicable.

Exclusion Criteria:

• Patients who have had prior tumor-directed therapy (including chemotherapy and/or radiation)
• Patients with a prior or current diagnosis of a malignant peripheral nerve sheath tumor.
• Patients who are considered too ill to participate as determined by their treating physician
• Patients who are pregnant or lactating

Participation in the study will be offered to patient's ages 2 years to 21 years seen for a routine visit in the Neurofibromatosis Clinic at Children's Memorial Hospital and Lurie Children's Hospital in Chicago.